[LE1] Lecture 5 Flashcards by Genella Alessandra Roallos

Biological process by which diploid or haploid cells undergo cell division and differentiation to form mature haploid gametes

GAMETOGENESIS

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The structure and physiology of gametes must accommodate three functions:

To survive in environment quite different from that of gonad
To recognize homologous cells of the other gender and participate in events related to fertilization
To provide sufficient genetic and cytoplasmic materials to support development of a new organism

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Four Major Phases of Gametogenesis:

OMRF

Origin of the germ cells and their migration to the gonads
Multiplication of the germ cells in the gonads through the process of mitosis
Reduction of the number of chromosomes by one-half by meiosis I (reductional division)
Final stages of maturation and differentiation of the gametes into spermatozoa or ova

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Germ Cells and their Origin
Anurans:
Urodeles:
Birds, reptiles, and mammals:

AVUMBE

Anurans: vegetal pole cytoplasm
Urodeles: mesodermal cells
Birds, reptiles and mammals: epiblast cells
Birds: germinal crescent
Mammals: posterior wall of yolk sac

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Cells/PGC needs to migrate from the endoderm to the hindgut to your ______________

genital ridges

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There could be an ovum without chromosomes, and then the other ovum could have double chromosomes

Nondisjunction, 1st meiotic division

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The chromosome is not distributed properly to the 4 cells.

Nondisjunction, 2nd meiotic division

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A flattened face, especially the bridge of the nose.
Almond-shaped eyes that slant up.
A short neck.
Small ears.
A single line across the palm (palmar crease)

TRISOMY 21 / Down Syndrome

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Low birth weight.
Small head and jaw.
An unusual-looking face and head.

TRINOMY 18 / EDWARDS SYNDROME

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Microcephaly (small head)
Cleft lip and/or cleft palate
Omphalocele (abdominal defect)
Spina bifida (open spine defect)
Microphthalmia (small eyes)
Anophthalmia (absent eyes)

TRISOMY 13 OR PATAU SYNDROME

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A webbed neck, broad chest, widely placed nipples

Turner Syndrome

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-oniums
-primary ___

Ploidy:
Chromatids:
Female:
Male:

Ploidy: Diploid
Chromatids: 2n before replication, 4n after replication
Female: Oocytogenesis (onium), Ootidogenesis (primary, meiosis I)
Male: Spermatocytogenesis (onium), Spermatidogenesis (primary, meiosis I)

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-secondary
-ids
-sperm/ovum

Ploidy:
Chromatids:
Female:
Male:

Ploidy: Haploid
Chromatids: 2n, n, n
Female: Ootidogenesis
Male: Spermatidogenesis, Spermiogenesis, spermiation

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F: Meiosis initiated _______ in a ________ population of cells

M: Meiosis initiated ____________ in a ______________ stem cell population

once, finite
continuously, mitotically dividing

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F: ______ gamete produced per meiosis

M: _______ gametes produced per meiosis

one, four

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F: Completion of meiosis ________________

M: Meiosis completed ________________

F: delayed for months or years; delayed until ovulation

M: in days or weeks

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F: Meiosis __________ at first, meiotic prophase is initiated and reinitiated in a smaller population of cells

M: Meiosis and differentiation proceed continuously without ____________________

arrested
cell cycle arrest

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F: Differentiation of gamete occurs while _________, in ___________________

M: Differentiation of gametes occurs while ___________, after _________________

diploid, first meiotic prophase haploid, meiosis ends

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F: All chromosomes __________ equivalent transcription and recombination during meiotic prophase

M: Sex chromosomes ________ from recombination and transcription during first meiotic prophase

exhibit
excluded

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In oogenesis, there are 2 arrests
- Oogonium in primary oocyte arrested in _________________

Prophase meiosis I

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_______________ is essential for pregnancy because it produces your progesterone and estrogen

Corpus luteum

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Ovum vs Spermatozoon

Store food:
Motility:
Number of gametes produced per 1 gametogenesis:
Number of gametes:

Store food:
Has stored yolk (food)
No stored food

Motility:
Relatively nonmotile
Highly motile

Number of gametes produced per 1 gametogenesis:
One ovum/1 primary oocyte
4 sperms/1 primary spermatocyte
Number of gametes:
Definite number
Indefinite number

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Process of development and maturation of male gametes (or spermatozoa) that starts in the embryonic testis and is completed in the sexually mature testis

SPERMATOGENESIS

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Five types of spermatogenic cells

spermatogonium
primary spermatocyte
secondary spermatocyte
spermatids
spermatozoa

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- Youngest cell in the series - Lie against the basal lamina of the seminiferous tubule

Spermatogonia

Round cells with ________ or _______ nucleus that occupy the 1st layer or basal layer of spermatogenic cells

round or oval

- Largest cells in the series - They are round cells that occupy the 2nd to 4th layer of the spermatogenic epithelium

Primary spermatocyte

They have a ______________ due to condensation of chromatin material into chromosomes

dense round nucleus

These cells are not commonly found in sections of seminiferous tubule because, as soon as they are formed from primary spermatocytes, they immediately divide into daughter spermatids

Secondary spermatocyte

Secondary spermatocytes enter ____________ immediately after being formed from primary spermatocytes during meiosis

meiosis II

______________ are small, round cells with round nucleus and nucleolus located above the layers of primary spermatocytes

Early spermatids

______________ are tall columnar cells that occur individually at regular intervals in the seminiferous tubule

Sertoli cells

Are cells with head, neck and tail (middle piece and principal piece), which form a mass in the lumen of the sexually mature seminiferous tubule

Spermatozoa

Middle piece of the tail connects with the neck and appears _________ than the principal piece of the tail

darker

Nucleus becomes __________ and _____________ Part: ________

compact and elongated Part: head

Centriole becomes located in the ________________

neck of the sperm

Centriole gives off a filament Part: _________________

axial filament of the tail

Golgi apparatus is transformed to become the _______________

acrosome

Mitochondria is arranged in _________ manner Part:______________________

helical spiral filament of middle piece

The plasma membrane of epididymal spermatozoa contains a complement of __________________ (proteins and carbohydrates)

surface molecules

The surface molecules in epididymal sperm become coated with _________________ (orange halos) that mask portions of the membrane molecules

seminal plasma proteins

When sperm are exposed to the female tract environment, these seminal plasma coatings, along with some of the surface molecules, are ___________, thus exposing portions of the molecules that can bind to the zona pellucida of the oocyte

removed

Synthesizing an ________________ that maintains a high concentration of testosterone inside the seminiferous tubule

androgen-binding protein

Maintaining the ______________ barrier

blood-testis

Creating an environment that is important in the ________________ of sperm cells

differentiation

Facilitating the release of __________________

mature spermatozoa

Degrading the _________________ that is shed during spermiogenesis

residual cytoplasm

If there is increased testosterone negative feedback will be sent to ______________ and ______________________

hypothalamus and anterior pituitary

A tight barrier to prevent foreign substances from entering, _________________ also prevent substances from entering

testicular macrophages

the counterpart of spermatogenesis in the female animal

oogenesis

_________ cytoplasmic divisions during meiotic divisions. Only ______ functional oocytes are produced per cycle and polar or residual bodies are produced

Unequal, one

Not seen in the ovary because they have differentiated into primary oocytes even before birth of the fetus

oogonia

- Undergo arrested stages after birth - Contained in the ovarian follicle that grows and eventually ruptures during ovulation to release the ______________

primary oocytes

primary oocytes divides to secondary oocyte during ____________

ovulation

Divides into an ovum and a second polar body during fertilization in the fallopian tube

Secondary oocytes

Microlecithal egg Amount of yolk: Yolk Distribution: Animal:

- Scanty - Isolecithal (equal distribution throughout the cytoplasm of the egg) - Placental mammal

Mesolecithal egg Amount of yolk: Yolk Distribution: Animal:

- Moderate amount - Increasing gradient from the animal to the vegetal pole of the egg - Amphibian

Macrolecithal egg Amount of yolk: Yolk Distribution: Animal:

- Large amount - Telolecithal (at the vegetal pole of the egg) - Bird

- Maturational changes at diplotene - Enlarged nucleus (germinal vesicle) - rRNA genes switched on

PREVITELLOGENIC

- Yolk platelets, lipochondria, and glycogen granules - Cortical granules: egg reaction to sperm - Polarity: pigmented animal pole, light vegetal pole

VITELLOGENIC

- Progesterone from follicular cells-Ca-MPF - Germinal vesicle break down - Completion of meiosis I - Release of 1st polar body then arrest at metaphase Il

MATURATION

Follicular Development ->

Primordial Follicle | Primary follicle | Secondary follicle | Tertiary follicle | Ovulation

Large cell with small, centrally located nucleus situated inside the follicle

Primary Oocyte

Cell membrane that appears as thin dark line that encloses the primary oocyte

Vitelline Membrane

A homegenous glycoprotein-material secreted by the primary oocyte, andcorona radiata, encloses the vitelline-membrane

Zona Pellucida

Single layer of follicular cells that surround the zona pellucida

Corona Radiata

Several layers of follicular cells that lie external to the corona radiata form a stalk that anchors the primary oocyte to the stratum granulosum

Cumulus Oophorus

Space or cavity containing. liquor follicull that separates the primary oocyte from the stratum granulosum, except at the area occupied by the cumulus oophorus - Formed by the rearrangement of follicular cells of the stratum granulosum

Antrum

Several layers of follicular cells form the peripheral wall of the growing follicle

Stratum Granulosum

- Outermost layer is overlaid with a _______________ - Stratum granulosum cells secrete _____________

basal lamina estrogen

Thin homogenous glycoprotein material that forms the outer limit of the ovarian follicle and demarcates the follicle from the theca folliculi or capsule

Basal Lamina

Inner cellular layer made up of cells that secrete androgens

Theca Interna

Outer fibrous layer made up of collagen fibers

Theca Externa

_____________ and _____________ work in both males and females; they allow oogenesis and spermatogenesis to proceed to production

Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH)

Cytoplasmic Components: Proteins: mRNA: Ribosomes and tRNA: Morphogenetic Factors: Protective Chemicals:

Proteins: energy, amino acids mRNA: to provide early instructions for development Ribosomes and tRNA: to aid in protein synthesis early in development Morphogenetic factors: molecules that affect differentiation of various cell types (can be localized to specific areas of the cell) Protective Chemicals: UV filters, DNA repair enzymes, antibodies (IgY in birds)

[LE1] Lecture 5 Flashcards

(75 cards)