DA1

Question 1

Developmental Anatomy studies….

Answer 1

the development of complex, multicellular organisms

Question 2

Development: ontogenetic

Answer 2

transformation of zygote into a new individual

Question 3

Development: phylogenetic

Answer 3

transformation of simple to complex organisms

Question 4

Challenges to development education:

Answer 4

-limited time -competition for “more important” courses -difficult subject matter for educators and unexposed students

Question 5

Developmental stages: Embryo

Answer 5

-from time of fertilization to completion of organogenesis -most critical stage!!!!!

Question 6

Developmental stages: organogenesis

Answer 6

the establishment of major organ primordia

Question 7

Developmental stages: fetus

Answer 7

reminder of prenatal development devoted to growth, differentiation and maturation of body systems

Question 8

Which domestic mammal has the longest gestation period?

Answer 8

Horse

Question 9

What are the three stages of early development?

Answer 9

1. Gametogenesis 2. Cleavage 3. Gastrulation

Question 10

Gametogenesis

Answer 10

First phase of early development Differentiation and maturation of primordial germ cells into gametes

Question 11

Origin of germ cells

Answer 11

Endoderm of the yolk sac

Question 12

Oogenesis

Answer 12

Maturation of primordial germ cells into female gametes

1. Oogonia differentiate into primary oocytes
2. Primary oocytes enter meiosis I and remain in “resting” stage until sexual maturity
   
   • (many oogonia and primary oocytes undergo apoptosis)
   • At birth, only “resting” primary oocytes are found in the ovary
3. Ovulatory hormones stimulate completion of meiosis I resulting in a haploid secondary oocyte and a polar body
4. Ovulated secondary oocyte enters meiosis II, and completion of meiosis II occurs ONLY if fertilization occurs

Question 13

Oogonia

Answer 13

primordial germ cells within female ebryonic gonad

Question 14

Once oogonia mature into a female gamete (egg) via meiosis, what happens next?

Answer 14

They continue mitotic divisions in the ovary until birth, then they stop!

Question 15

Oogenic meiosis is different than spermatogenic meiosis because….

Answer 15

two gametes have special attributes

Question 16

In the dog and fox, primary oocytes are released at…..

Answer 16

ovulation

Question 17

Multinucleated ovarian follicles usually….

Answer 17

degenerate

Question 18

Age-related damage to oocytes

Answer 18

meiotic errors during “resting” stage

Question 19

Ovulation can either be _____ or _____.

Answer 19

Spontaneous or induced

Question 20

Meiosis

Answer 20

reduction-division process –> haploid cells

Question 21

Spermatogenesis

Answer 21

Maturation of primordial germ cells into male gametes

1. Spermatogonia continue mitosis then enter “resting” stage of meiosis I until puberty
2. At puberty, spermatogonia differentiate into primary spermatocytes
3. Meiosis I may be completed at any time resulting in two equal haploid secondary spermatocytes
4. Secondary spermatocytes complete meiosis II –> four haploid spermatids
5. Spermatids undergo spermiogenesis (maturation) to become motile spermatozoa

Question 22

Spermatogenesis is a _______ process.

Answer 22

continuous

Question 23

Capacitation

Answer 23

Physiological changes of spermatozoa in female genital tract necessary for fertilization

Question 24

Gametogenesis: differential synopsis

Oogenesis vs Spermatogenesis

Answer 24

• Oogenesis: one daughter cell becomes ovum and 3 polar bodies
• Spermatogenesis: each daughter cell develops into a spermatozoon
• Oogenesis: process begins before birth
• Spermatogenesis: process begins at puberty
• Oogenesis: one (several) matures monthly (seasonally)
• Spermatogenesis: millions are produced at a time

Question 25

Fusion of gametes --\> zyogte Occurs in: \_\_\_\_\_\_\_\_\_\_\_

Answer 25

Occurs within the zona pellucida, specifically inside the oocyte.

Question 26

Steps of fertilization

Answer 26

1. Penetration of zona pellucida by spermatozoa 2. Fusion of gametes membranes 3. Integration of genetic material

Question 27

Results of fertilization

Answer 27

* Restoration of diploid chormosome number * sex determination of individual * Initiation of cleavage

Question 28

Sex determination in birds, snakes, some insects

Answer 28

The males are homogametic (ZZ) and females are ZY

Question 29

Sex determiniation in crocodiles, turtles

Answer 29

Determined by incubation temperature of eggs

Question 30

Second stage of early development: cleavage Morula

Answer 30

* A spherical mass of cells (blastomeres)formed by rapid mitotic division * The size of the embryo does not change because zona pellucida is STILL present. * The zona pellucida prevents adherence and embryo rejection by internal immune system

Question 31

Second stage of early development: cleavage **Early blastocyst**

Answer 31

* **Blastula:** A single layer of cells lining a central cavity called blastocyst * Zona pellucida degenerates and implantation follows * Time and form of implantation differ among species

Question 32

Second stage of early development: cleavage **Late Blastocyst**

Answer 32

* Segregation of blastomeres: * **Trophoblast:** outer single-cell layer that forms the fetal membranes * **Inner cell mass:** central core of cells that forms the embryo * At blastocyst stage blastomeres have restricted developmental potneital

Question 33

Third stage of early development: Gastrulation

Answer 33

* Formation of germ layers: * Cells if inner cell mass delaminate and form **hypoblast** surrounding trophoblast * Hypoblast cells become **extraembryonic endoderm** (forms yolk sac) * Remainder of inner cells above hypoblast form **epiblast** * Epiblast splits to form: * **Extraembryonic** epiblast which lines amniotic cavity * **Embryonic epiblast** which is the source of all three germ layers

Question 34

Derivative of ectoderm

Answer 34

Epidermis and nervous system

Question 35

Derivatives of mesoderm

Answer 35

* Cardiovascular system * urinary and genital systems/blood cells * most of connective and muscular tissue

Question 36

Derivatives of endoderm

Answer 36

* Digestive and respiratory tracts * Urinary bladder, tympanic cavity * Parenchyma of thyroid and parathyroid glands