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Flashcards in Spermatogenesis and Oogenesis Deck (55)
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1

Spermatogenesis

Process of formation of sperm
- begins at puberty
- rarely totally ceases

2

Where is the site of sperm formation?

Seminiferous tubule of the testicle

3

Events of spermatogenesis

Start with 2n chromosome (spermatogonium) --> mitotic division = primary spermatocyte (2n) --> at end of meiosis 1 = secondary spermatocyte (2 1n chromosomes) --> meiosis 2 = early spermatids (4 n chromosomes) --> differentiation, seroli cells provide nutrients --> sperm cells (spermatozoa)

4

Spermatogenesis progress from the cortex of the semineferous tubule and ends in the _____

Lumen
- where fully formed sperm cells are released

5

Each spermatogonia produces _____

4 sperm cells
- 1:4 ratio

6

Events of oogonium

Begin with primary oocyte (2n) --> meiosis 1 = secondary oocyte and first polar body --> secondary ooctye undergoes meiosis 2 = ootid and second polar body --> ootid differentiates into 1 ovum

7

Females only produce _____ from an oogonium

1 ovum
- do not undergo mitosis!!!

8

Seasonality's effect on spermatogenesis

Produce sperm throughout the year, but may produce more during the species' season of breeding
- high vs low production

9

Meiosis 1

2 haploid cells form
- chromosomes are still double
- telophase and cytokinesis with cleavage furrow

10

Meiosis 2

Sister chromatids separated
- 4 haploid daughter cells result
- contains single chromosomes
- prophase 2 - telophase 2

11

Epididymis

Storage of produced sperm

12

Blood flow of the testicle

Enters testicular artery
- artery and venous return are intertwined = pampiniform plexus
- acts to cool the blood entering the testis

13

Testosterone secreted by Leydig cells has a _______ feedback

Negative

14

LH stimulates Leydig cells to secrete ______

Testosterone

15

FSH stimulates Sertoli cells to produce _____

Inhibin
- also converts testosterone to estrogen
- helps with spermiogenesis

16

Males: LH released from AP in a ______ fashion

Pulsatile
- only have a tonic center, no surge
- prevents refractoriness to sustained LH

17

Testosterone secretion is ______ and ______

Short; pulsatile
- elevated testosterone in testis is essential for spermatogenesis

18

Pampiniform plexus helps maintain high levels of ______ in the testis

Testosterone

19

Large spikes of _____ has a negative feedback and ______ LH production

Testosterone; downregulates

20

Is peripheral blood a good indicator of the testicular environment?

No, 500x dilution of testosterone, estrogen, and DHT by systemic circulation

21

What are the 3 biological events involved in spermatogenesis?

- mitosis
- meiosis
- spermiogenesis

22

Mitosis

Proliferation phase which allows for continual supply of germ cells

23

Meiosis

- allows for diploid to haploid
- allows for crossing over
- assures genetic diversity

24

Spermiogenesis

Dramatic morphological changes from spermatids to spermatozoa

25

The proliferation phase of spermatogenesis occurs in the ______ area of the seminiferous tubules

Basal

26

Meiosis and differentiation of spermatogenesis occurs in the ______ area of the seminiferous tubules

Adluminal

27

______ envelop the developing spermatogonia

Seroli cells

28

What process of spermatogenesis is very heat sensitive?

Maturation of spermatogonia into primary spermatocytes
- mitosis

29

Primary spermatocytes undergo _____ and form ______

Meiosis 1; secondary spermatocytes
- haploid!

30

Secondary spermatocytes undergo ____ and become ______

Meiosis 2; spermatids