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Flashcards in EXAM I Deck (56)
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1

Following fertilization, when do the primordial germ cells first appear?

Endodermal layer of yolk sac

24 hrs after fertilization

2

Trace the migration route of the primordial germ cells into the developing gonads from the yolk sac

Endodermal yolk sac ---> hind gut epithelium via dorsal mesentery ---> developing gonads

3

What are the stages of meiosis? List substages of prophase with what occurs at each stage

PMAT I

PMAT II

(Little Zebras Play Dirty Deeds)

Leptotene - chrom begin to coil, each chrom = 2 chromatids

Zygotene - homologous chrom pair (synapsis), synaptonemal complex forms

Pachytene - tetrads, start of crossing-over

Diplotene - crossing-over, chiasmata well defined

Diakinesis - finish crossing-over, nuclear membrane disrupted, spindle apparatus

 

 

 

4

What are the major events in meiosis?

List the major results of meiosis?

  • Synapsis (pairing of homo. chrom.), crossing-over, two cell divisions w/ 1 DNA replication cycle (n)
  • Non-identical and haploid daughter cells, increase in cell number

5

Define aneuploidy and euploidy, what are the types?

Euploidy - changes in complete set # of chromosomes

  • Monoploidy, Diploidy (normal), Polyploidy

Aneuploidy - abnormal chrom. number (via nondisjunction)

  • Monosomy, Trisomy

6

Compare the total number of oocytes that are present early in embryonic development to the number present at birth and prior to puberty.

Embryonic midterm  - 7 million

Birth - 2 million 

Puberty - 400,000 (arrested in diplotene)

Post-puberty - 400

Most become atretic

7

Describe the structure/layers of the mature follicle

external ---> internal

Theca externa - produce angiogenesis factor

Theca interna - LH receptors, secrete testosterone

Membrana granulose

Mural granulosa cells - FSH receptors

Antrum

Cumulus/Oophorus cells - facilitates release of ovum at ovulation

Zona pellucida 

Oocyte

8

Describe the meiotic state of the oocyte at puberty and prior to ovulation

Until puberty - diplotene of prophase I (primary oocyte)

Pre-Ovulation - metaphase II (until fertilization)

9

What is the role of LH in ovulation?

LH surge occurs causes ovulation; resuming of meiosis to arrest in Metaphase II shuts down gap junctions b/w granulosa cells and oocyte, reducing [cAMP], allowing MPF activation

10

What are the factors that lead to meiotic arrest at the diplotene stage of meiosis

  1. Hight [cAMP] from oocyte and follicular cells (inactivating MPF)
  2. cGMP from follicular cells that inactivate phosphodiesterase 3A in oocyte (preventing the conversion of cAMP to 5'AMP, maintains high [cAMP]

11

What are the fates of the follicle after ovulation occurs?

Becomes the corpus luteum and secretes progesterone

Eventually degenerates

12

Define, compare, and contrast spermatogenesis and spermiogenesis

Spermatogenesis - Development of mature sperm 

Spermiogenesis - maturation of spermatids to motile spermatozoa

13

List the stages of spermatogenesis (5)

  1. Primordial germ cells (2N); developing yolk sac
  2. Spermatogonia (2N); Type A stem cells, Type B
  3. Primary Spermatocytes (2N, 4c); meiosis I
  4. Secondary Spermatocytes (N, 2c); meiosis II
  5. Spermatids (N, 1c); x4 cells

14

List the two major differences between one cycle of oogenesis and once cycle of spermatogenesis

Two secondary spermatocytes (1n, 2c)

1 secondary oocyte + polar body

15

What is the location and function of the cells of Leydig?

Interstitial cells inside the testis

Produce testosterone

16

List the four stages of spermiogenesis and the major events that occur during each of the four stages

GCAM - Girls Call Abnormal Men

  1. Golgi phase - proacrosomal vesicles, acrosomal vesicles
  2. Cap phase - mature acrosome forms a cap over nucleus
  3. Acrosomal phase - sperm rotates so that acrosomal pole faces wall of seminiferous tubule, cytoplasm eliminated from tail for motility
  4. Maturation phase - completion of flagellum and nuclear condensation

17

Where are sertoli cells located?

Seminiferous tubules of the testes

18

What are the functions of the sertoli cells? (6)

  • Physical support and maintenance
  • Maintain and coordinate spermatogenesis
  • Secrete estrogen, inhibin, and anti-Mullerian factor
  • Maintain the blood-testes-barrier
  • Secrete tubular fluid
  • Phagocytize residual bodies of sperm cells

19

What is the role of testosterone in the blood testes barrier?

Stimulates the formation of a new BTB closer to the basal lamina

20

What is the action of LH on interstitial cells and Sertoli cells in regards to sperm cell production?

  • LH - activates LH receptors on interstitial cells of Leydig, causing cholesterol synthesis
  • Sertoli cells receive the testosterone and to secondary sex tissues

21

Based on your knowledge of paralogous groups, which gene would be expressed most anteriorly in the embryo?

Hoxa-13

Haxc-9

Hoxd-13

Hoxb-1

Hoxb-6

Hoxb-1

22

Which of the following produces testosterone in the testis?

Sertoli

Leydig

Granulose

Spermatogonia

Cells of Leydig

23

What forms the corpus luteum?

Corona radiata

Thecal

Granulosa

Thecal and granulosa

Granulosa Cells

Thecal Cells

24

What the the site of fertilization?

Ampulla

Isthmus

Ampulla

25

In mammalian embryo, unlike non-mammalian and invertebrates, most transcription via the embryonic genome as opposed to maternal genome, occurs as early as which...

Zygote

4-Cell Stage

Blastula

Gastrula

4-Cell Stage

26

In drosophila, from which of the following categories are mRNAs derived from maternal genome rather than embryonic?

Egg-polarity genes

Pair rule genes

Homeotic genes

Gap genes

Egg-polarity genes

27

Which of the following is a TF

FGF

Pax

TGF

Notch Wnt

Pax

28

Zinc fingers or helix loop helix arrangements are characteristic of members of which class of molecules?

Proto Oncogenes

Signaling Molecules

Receptors

Transcription factors

None of the above

TFs

29

Shh is produced in which signaling centers

Notocord

Intestinal portals

Floor plate of the neural tube

Zone of polarizing activity in limb bud

All of the above

All of the above

30

The principal energy source for ejaculated spermatozoa is

Prostatic acid phosphatase

Internal glucose

Prostatic citric acid

Fructose seminal vesicle fluid

 

Fructose seminal vesicle fluid