Histology Term Test 2 Flashcards
(180 cards)
1
Q
What is embryology?
A
The study of prenatal development.
2
Q
What is prenatal development?
A
The period from the start of pregnancy to the birth of the child.
3
Q
What is postnatal development?
A
The period of growth and development that occurs after birth.
4
Q
What is the gestational period?
A
The length of pregnancy after the first day of the last menstrual period (LMP), usually expressed in weeks and days.
5
Q
What are the 3 periods of prenatal development?
A
Pre-implantation, embryonic, and fetal.
6
Q
When is the pre-implantation period?
A
During the first week.
7
Q
What happens during pre-implantation?
A
Fertilization, implantation, and division.
8
Q
What is produced during pre-implantation?
A
Zygote and blastocyte.
9
Q
When does the embryonic period occur?
A
From the 2nd week to the 8th week.
10
Q
What happens during the embryonic period?
A
Induction, proliferation, differentiation, morphogenesis, and maturation.
11
Q
What is produced during the embryonic period?
A
Disc, embryo, and folded embryo.
12
Q
When does the fetal period occur?
A
From the 3rd to the 9th month.
13
Q
What happens during the fetal period?
A
Maturation.
14
Q
What is produced during the fetal period?
A
Embryo and fetus.
15
Q
What are the key points of pre-implantation?
A
Fertilization, cleavage, morula.
16
Q
What is fertilization?
A
Ovum + sperm = zygote.
17
Q
What is a zygote?
A
Fertilized egg: 46 chromosomes.
18
Q
What is cleavage?
A
Zygote undergoes mitosis.
19
Q
What is a morula?
A
A solid ball of cells that makes up an embryo after zygote.
20
Q
What is the first trimester?
A
Weeks 1-12; pre-implantation to embryonic.
21
Q
What are the second and third trimesters?
A
Fetal period.
22
Q
What are the 5 physiological processes of the embryonic stage?
A
Induction, proliferation, differentiation, morphogenesis, maturation.
23
Q
What is induction?
A
The action of one group of cells on another that leads to the establishment of a developmental pathway.
24
Q
What is proliferation?
A
Controlled cellular growth and accumulation of byproducts.
25
What is differentiation?
Change in identical embryonic cells to become distinct structurally and functionally.
26
What is morphogenesis?
Development of specific tissue structure or differing form due to embryonic cell migration or proliferation and inductive interactions.
27
What is maturation?
Attainment of adult function and size due to proliferation, differentiation, and morphogenesis.
28
What is appositional growth?
Tissue enlarges its size by the addition of layers on the outside of a structure.
29
What is interstitial growth?
Occurs from deep within a tissue or organ.
30
What are the 3 types of differentiation?
Cytodifferentiation, histodifferentiation, morphodifferentiation.
31
What is cytodifferentiation?
Development of different cell types.
32
What is histodifferentiation?
Development of different histologic tissue types within a structure.
33
What is morphodifferentiation?
The development of different forms, making up its structure or shape for each organ or system.
34
What are teratogens?
Any agent that can cause birth defects or abnormalities in a developing fetus.
35
What are some drug teratogens?
Ethanol, tetracycline, phenytoin sodium.
36
What are some chemical teratogens?
Methylmercury, polychlorinated biphenyls.
37
What are some infection teratogens?
Rubella virus, syphilis, herpes, HIV.
38
What are some radiation teratogens?
High levels of ionizing type.
39
What are the clinical considerations for clients with Down syndrome?
Increased levels of periodontal disease, delayed tooth eruption, fewer teeth present, microdontia.
40
What is produced during prenatal development weeks 1-4?
| (3)
Blastocyst, bilaminar layer disc, trilaminar layer disc.
41
When does the blastocyst form?
After a week of cleavage.
42
What are the components of the blastocyst?
Trophoblast and embryoblast.
43
What is the trophoblast?
Peripheral cells that form the placenta.
44
What is the embryoblast?
Inner cell mass that forms the embryo.
45
When does the bilaminar layer disc form?
During the second week.
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What are the components of the bilaminar layer disc?
Epiblast layer and hypoblast layer.
47
What is the epiblast layer?
The superior layer that forms the yolk sac.
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What is the hypoblast layer?
The inferior layer that forms the amnion.
49
When does the trilaminar layer form?
During the third week.
50
What are the components of the trilaminar layer disc?
Ectoderm, mesoderm, endoderm.
51
What does the ectoderm develop into?
Produces sense organs, nerves, and glands.
52
What does the mesoderm develop into?
Develops into dermis, bone, lymphatics, blood cells, bone marrow, cartilage, reproductive and excretory organs.
53
What does the endoderm develop into?
The lining of the digestive and respiratory systems.
54
Where do mesoderm and endoderm migrate from?
From the epiblast layer.
55
What does 'gives rise to' mean?
Leads to the development or creation of the second thing.
56
What is cleavage?
Cells divide constantly.
57
What is the oropharyngeal membrane?
Membrane at the cephalic end of the embryo, separates the stomodeum from the foregut.
58
What is the stomodeum?
Primitive mouth and parts of the face and neck.
59
What is the foregut?
Anterior part of the future digestive tract or **primitive pharynx.**
60
What is a primordium?
The earliest stage of development of an organ or tissue.
61
What do the midgut and hindgut form?
The rest of the mature pharynx as well as the remainder of the digestive tract.
62
When do the branchial (pharyngeal) arches develop?
During the 4th week.
63
What happens during week 4?
The face and its associated tissues begin to form.
64
What is the 1st branchial arch? what nerve and cartilage is it associated with?
Also known as the mandibular arch, associated with the trigeminal nerve and Meckel's cartilage.
65
Does the cartilage of the 1st branchial arch disappear?
Yes, it disappears and forms the middle ear bones.
66
What is the future site of the 1st branchial arch?
Lower face and lips, mandible and mandibular teeth, muscles of mastication, and associated mandibular muscle.
67
What does the mesoderm of the 1st branchial arch form?
Muscles of mastication, middle ear, and soft palate movement.
68
What are the incus and malleus?
Bones of the middle ear formed from the 1st branchial arch.
69
What is the 2nd branchial arch?
Also known as the hyoid arch.
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muscles of mastication (4)
masseter
temporalis
medial pterygoid
lateral pterygoid
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What is the nerve associated with the 2nd branchial arch?
Facial nerve.
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What is the cartilage of the 2nd branchial arch?
Reichert cartilage, which mostly disappears.
72
What is interesting about the Reichert cartilage?
It mostly disappears but the perichondrium remains to form the styloid process, lesser horn of hyoid bone, upper part of the body of hyoid bone, and stylohyoid ligament.
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What does the mesoderm of the 2nd branchial arch form?
Muscles of facial expression.
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What does the 3rd branchial arch develop into?
Lower body of the hyoid bone and posterior portion of the tongue.
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What nerves are involved in the 3rd branchial arch?
Glossopharyngeal and stylopharyngeal.
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What do the 4th and 6th branchial/pharyngeal arches develop into?
Laryngeal cartilages and vagus nerves.
77
What do the maxillary processes develop into?
Midface, upper lip side, cheeks, secondary palate, posterior part of maxilla, zygomatic bones, and part of the temporal bones.
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What do the mandibular processes develop into?
Lower lip and lower face.
79
What is a placode?
Specialized ectoderm for the development of the sense organs.
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What is the otic placode?
Future internal ear.
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What is the lens placode?
Future eyes.
82
What is the nasal placode?
Responsible for smell.
83
What is the philtrum?
Vertical groove that runs from the bottom of the nose to the top of the upper lip.
84
Where is the philtrum developed from?
Medial nasal processes.
85
What is palatal fusion?
The completion of the final palate, involving the fusion of swelling or tissue from **different** surfaces of the embryo.
| **different surfaces
86
When does palatal formation begin?
During the fifth week and ends at the twelfth week.
87
What happens when palatal formation is interrupted?
Cleft palate or cleft lip may occur.
88
What is the intermaxillary segment formed from? during what week and gives rise to what?
Formed from the internal fusion of medial nasal processes during the fifth week, giving rise to the primary/primitive palate.
89
When does the primary/primitive palate develop?
From the 5th to the 6th week.
90
What does the primary/primitive palate initially serve as?
It partially separates the developing oral cavity proper and nasal cavity.
91
What does the primary/primitive palate later turn into?
The premaxillary part of the maxilla (1/3 of hard palate) and maxillary incisors.
92
When and How is the secondary palate formed?
6th to 8th week: The bilateral maxillary processes give rise to two palatal shelves that elongate and move medially.
93
What does the secondary palate form into?
2/3 of the hard palate, canines, posterior teeth, soft palate, and uvula.
94
When does the developmental process of the tongue occur?
From the 4th to the 8th week.
95
What is the tuberculum impar? when is it formed? located where and formed where?
A triangular median swelling that forms during the 4th week, located midline and formed on the mandibular arch.
96
What is the first thing that happens during tongue development from the 4th to the 8th week?
Two oval lateral lingual swellings develop on each side of the tuberculum impar, which fuse to form the anterior 2/3 of the tongue.
97
What produces the median lingual sulcus?
The fusion of the two lateral lingual swellings.
98
What is the second thing that happens during tongue development from the 4th to the 8th week?
The copula becomes evident and overgrows the hyoid arch, forming the posterior 1/3 of the mature tongue.
99
What happens during the 8th week of tongue development?
The copula merges with the lateral lingual swellings, causing the sulcus terminalis.
100
What is the median lingual sulcus?
A superficial demarcation in the middle of the tongue formed by the fusion of the two lateral lingual swellings.
101
What is the sulcus terminalis?
A V-shaped structure that borders the base of the tongue and the body.
102
What is the foramen cecum?
A small pit-like depression at the point of the sulcus terminalis.
103
What are the stages of tooth development?
Initiation, bud, cap, bell, apposition, maturation.
104
When does the initiation stage occur?
During the 6th week.
105
What is the main physiological process for the initiation stage?
Induction.
106
What happens during the initiation stage?
The stomodeum is lined by ectoderm, which influences mesenchyme to initiate odontogenesis.
107
What does the outer part of the ectoderm give rise to during the initiation stage?
The oral epithelium.
108
What is the ectomesenchyme?
The tissue deep to the forming oral epithelium.
109
What does the basement membrane do during the initiation stage?
It separates the oral epithelium from the ectomesenchyme.
110
What happens in the later part of the initiation stage? what week does this happen?
On the 7th week, the oral epithelium grows deeper into the ectomesenchyme and produces a layer called the Dental Lamina.
111
When does the bud stage occur?
At the beginning of the 8th week.
112
What is the main physiological process during the bud stage?
Proliferation (controlled cellular growth).
113
What happens during the bud stage?
Growth of the dental lamina into a bud that penetrates the growing ectomesenchyme.
114
What is the result of proliferation during the bud stage?
Tooth bud, 10 on each arch.
115
What happens to the ectomesenchyme and basement membrane during the bud stage?
Ectomesenchyme proliferates while the basement membrane remains between the lamina and the ectomesenchyme.
116
What does the tooth bud turn into?
Tooth germ.
117
What is anodontia?
The absence of a single tooth during the initiation stage.
118
When does the cap stage occur?
From the 9th to the 10th week.
119
What is the physiological process during the cap stage?
Morphogenesis.
120
What happens during the cap stage?
Unequal growth of different parts of the tooth bud.
121
What is a primordial?
A structure or tissue in the earliest stage of development.
122
What is developed during the cap stage?
A tooth germ, which includes the enamel organ, dental papilla, and dental sac.
123
What is the enamel organ in a tooth germ? what will it become?
The deepest part of a tooth bud that is cap-shaped; it will become the enamel.
124
What is the enamel knot?
A region noted in molars' enamel organ orchestrating posterior crown form.
125
What is the dental papilla? what is it the remnant of?
Remnant of the ectomesenchyme, now a mass within the concavity of the cap of the enamel organ.
126
What is the future structure of the dental papilla?
Dentin and pulp.
127
What happens to the basement membrane during the cap stage?
It remains between the enamel organ and the dental papilla, becoming the dentinoenamel junction.
128
What is the dental sac?
Surrounds the developing tooth (enamel organ and dental papilla) and becomes cementum, PDL, and alveolar bone.
129
When does the initiation of permanent dentition begin? where does it start and proceed?
During the tenth week of prenatal development, starting at the midline and proceeding posteriorly.
130
What is the successional dental lamina?
An extension of the dental lamina into ectomesenchyme forming succedaneous permanent teeth.
131
What are succedaneous teeth?
Permanent teeth that replace primary teeth (1s-5s).
132
What are nonsuccedaneous teeth?
Permanent teeth that do not replace a primary tooth (6s and 7s).
133
When does the bell stage occur?
From the 11th to the 12th week.
134
What is the main physiological process during the bell stage?
Differentiation (proliferation and morphogenesis also occur).
135
What are the 4 cell types due to differentiation during the bell stage?
Outer enamel epithelium
stellate reticulum
stratum intermedium
inner enamel epithelium
136
What is the outer enamel epithelium?
The protective barrier for the enamel organ.
137
What is the inner enamel epithelium?
The innermost tall, columnar cells of the enamel organ that will differentiate into **ameloblasts** to form enamel matrix.
138
What is between the outer enamel epithelium and inner enamel epithelium?
Stellate reticulum and stratum intermedium.
139
What does the stellate reticulum do?
Provides space for forming enamel.
140
What does the stratum intermedium do?
Flat cuboidal cells that support enamel mineralization.
141
What do the stellate reticulum and stratum intermedium do?
Help support the future production of enamel matrix.
142
What happens to the dental papilla during the bell stage?
It consists of two types of tissue: outer cells of the dental papilla and central cells of the dental papilla.
143
What are odontoblasts? where were they differentiated from?
Dentin-secreting cells that differentiate from the outer cells of the dental papilla.
144
What do the central cells of the dental papilla become?
The primordium of the pulp.
145
What happens to the dental sac during the bell stage?
It undergoes histodifferentiation into cementum, PDL, and alveolar process.
146
What is the periodontium?
Cementum, PDL, and alveolar process.
147
What is the apposition stage?
The secretory stage during which enamel, dentin, and cementum are secreted in successive layers, resulting in appositional growth.
148
What is the maturation stage?
The final stage of odontogenesis when matrices of hard dental tissue types fully mineralize.
149
When does primary dentition develop?
During the embryonic and fetal period, approximately 6 weeks.
150
When does permanent dentition mostly develop?
During the fetal period.
151
What organ has the longest development period?
Teeth.
152
What types of interaction are involved in the initiation of tooth development?
Interaction of ectoderm and mesenchyme.
153
What are the final stages of odontogenesis?
1. Apposition stage: secretory stage where enamel, dentin, and cementum are secreted in successive layers.
2. Maturation stage: final stage when matrices of hard dental tissue types fully mineralize.
154
Which organ has the longest development period?
Teeth.
155
What two types of embryonic cells interact in tooth development?
Oral epithelial cells that line the stomodeum and mesenchymal cells.
156
Why is the dental lamina important in tooth development?
1. Blueprint
2. Initiates development
3. Directs tooth germ formation
4. Forms the enamel organ.
157
What is microdontia?
Abnormally small teeth during the budding stage.
158
What are peg lateral and peg molar?
Small teeth.
159
What is dens in dente?
Tooth within a tooth, enamel organ abnormally invaginated during the cap stage.
160
What is gemination?
During the cap stage, a single tooth germ attempts to divide into two, appearing as two crowns joined together by a notched incisal area.
161
What is fusion?
During the cap stage, the union of two adjacent tooth germs.
162
What is enamel dysplasia?
Faulty development of enamel during the maturation stage.
163
What is enamel hypoplasia?
Reduction of enamel matrix quantity during the maturation stage.
164
What is enamel hypocalcification?
Reduction in the quality of enamel maturation during the maturation stage.
165
What is amelogenesis imperfecta?
Thin or no enamel during the maturation stage.
166
What do enamel organs turn into and what do they secrete?
Enamel organs turn into ameloblasts, which secrete enamel.
167
What does the dental papilla turn into and what does it secrete?
Dental papilla turns into odontoblasts, which secrete dentin and pulp.
168
What surrounds the enamel organ and dental papilla?
Dental sac.
169
What does the dental sac secrete?
Cementoblasts, which secrete cementum.
170
What is the cervical loop responsible for?
Root development.
171
in terms of root development, What is the role of the stellate reticulum?
Root dentin.
172
What does the Hertwig epithelial root sheath do?
Shapes the roots and induces dentin formation.
173
How does the cervical loop give rise to the Hertwig epithelial root sheath?
The cervical loop grows deeper into the surrounding ectomesenchyme of the dental sac, elongating and moving away from the newly completed crown area.
174
Where are rests of mallesez formed from?
Formed from the disintegration of the root sheath and root dentin.
175
Where are the rests of Malassez located and what do they do?
Located in the mature PDL, they are involved in repairing and regeneration.
176
What is cementogenesis?
**Appositional **growth of the cementum in the root area.
177
What is amelogenesis?
Process of enamel formation on teeth.
178
What are preameloblasts?
Immature cells that differentiate into ameloblasts.
179
What are the key functions of preameloblasts?
1. Cell proliferation: division
2. Differentiation into mature ameloblasts
3. Enamel matrix secretion.
