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KCUMB Embryology > EXAM I > Flashcards

EXAM I Flashcards

1
Q

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

A

Endodermal layer of yolk sac

24 hrs after fertilization

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2
Q

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

A

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

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3
Q

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

A

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

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4
Q

What are the major events in meiosis?

List the major results of meiosis?

A
  • 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
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5
Q

Define aneuploidy and euploidy, what are the types?

A

Euploidy - changes in complete set # of chromosomes

  • Monoploidy, Diploidy (normal), Polyploidy

Aneuploidy - abnormal chrom. number (via nondisjunction)

  • Monosomy, Trisomy
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6
Q

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

A

Embryonic midterm - 7 million

Birth - 2 million

Puberty - 400,000 (arrested in diplotene)

Post-puberty - 400

Most become atretic

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7
Q

Describe the structure/layers of the mature follicle

A

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

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8
Q

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

A

Until puberty - diplotene of prophase I (primary oocyte)

Pre-Ovulation - metaphase II (until fertilization)

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9
Q

What is the role of LH in ovulation?

A

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

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10
Q

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

A
  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]
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11
Q

What are the fates of the follicle after ovulation occurs?

A

Becomes the corpus luteum and secretes progesterone

Eventually degenerates

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12
Q

Define, compare, and contrast spermatogenesis and spermiogenesis

A

Spermatogenesis - Development of mature sperm

Spermiogenesis - maturation of spermatids to motile spermatozoa

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13
Q

List the stages of spermatogenesis (5)

A
  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
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14
Q

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

A

Two secondary spermatocytes (1n, 2c)

1 secondary oocyte + polar body

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15
Q

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

A

Interstitial cells inside the testis

Produce testosterone

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16
Q

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

A

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
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17
Q

Where are sertoli cells located?

A

Seminiferous tubules of the testes

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18
Q

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

A
  • 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
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19
Q

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

A

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

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20
Q

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

A
  • LH - activates LH receptors on interstitial cells of Leydig, causing cholesterol synthesis
  • Sertoli cells receive the testosterone and to secondary sex tissues
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21
Q

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

A

Hoxb-1

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22
Q

Which of the following produces testosterone in the testis?

Sertoli

Leydig

Granulose

Spermatogonia

A

Cells of Leydig

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23
Q

What forms the corpus luteum?

Corona radiata

Thecal

Granulosa

Thecal and granulosa

A

Granulosa Cells

Thecal Cells

24
Q

What the the site of fertilization?

Ampulla

Isthmus

A

Ampulla

25
Q

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

A

4-Cell Stage

26
Q

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

A

Egg-polarity genes

27
Q

Which of the following is a TF

FGF

Pax

TGF

Notch Wnt

A

Pax

28
Q

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

A

TFs

29
Q

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

A

All of the above

30
Q

The principal energy source for ejaculated spermatozoa is

Prostatic acid phosphatase

Internal glucose

Prostatic citric acid

Fructose seminal vesicle fluid

A

Fructose seminal vesicle fluid

31
Q

Of the barriers to sperm survival and transport within the female reproductive tract, low pH is most important in the:

Upper uterine tube

Lower uterine tube

Uterine cavity

Cervix

Vagina

A

Vagina

32
Q

During the menstrual cycle a sharp spike in plasma levels of which of the following levels just before ovulation is responsible for ovulation?

FSH

LH

Estrogen

Progesterone

Estradiol-17 beta

A

LH

33
Q

Transcription of which of the following genes is required to permit cleavage to proceed to the 2-cell stage in embryos?

Nanog

4-Oct

Cdx 2

Sox 2

A

4-Oct

34
Q

The principal inductor in primary neural induction is the:

Hypoblast

Primitive streak

Extraembryonic mesoderm

Notochordal process

Embryonic ectoderm

A

Notochordal process

35
Q

Cells of which germ layer are not present in the oropharyngeal membrane?

Ectoderm

Mesoderm

Endoderm

All are present

A

Mesoderm

36
Q

Brachyury, a deficiency in caudal tissues in the body, is caused by a mutation in what gene?

Lim-1

Noggin

T

Sonic hedgehog

Activin

A

T

37
Q

Hypoblast is a bilaminar, early embryo gives rise to which of the following tissue types?

Extraembryonic only

Embryonic only

Embryonic and extraembryonic

Neither

A

Extraembryonic only

38
Q

In meiosis, pair of homologous chromosomes begins during which of the following stages of prophase I?

Letotene

Zygotene

Pachytene

Diplotene

A

Zygotene

39
Q

Which of the following description best describes the oogonium and the ovary during the early fetal period?

Diploid, no follicle

Diploid, few follicle cells

Haploid, no follicle

Haploid, few follicle cells

A

Diploid, no follicle

40
Q

Inhibin released by the granulose cells during the mammary cycle inhibits secretions of gonadotropins especially FSH. Resulting in which of the following

Regression of the corpus luteum

A

Regression of the corpus luteum

41
Q

Splitting of the blastocyst during early development, results in the two complete blastocyst enclosed within a single trophoblast is the most common mode of twinning. Assuming complete normal identical twins result of what development property is illustrated?

Differentiation

Determination

Regulation

Morphogenesis

A

Regulation

42
Q

During spermatogenesis, histone is replaced by which of the following, to allow better packing of the condensed chromatin in the head of the spermatozoon?

Inhibin

Prostaglandin E

Testosterone

Protamine

Androgen-binding protein

A

Protamine

43
Q

Which cell type is located outside the blood testis barrier?

Spermatozoon

Secondary spermatocyte

Spermatid

Primary spermatocyte

Spermatogonium

A

Spermatogonium

44
Q

Which of the following cells normally participates in mitotic division?

Primary oocyte

Oogonium

Primary spermatocyte

Spermatid

Secondary spermatocyte

A

Oogonium

45
Q

Role of Cdx2 gene

A

Trophoblast cell differentiation

46
Q

State the role of Oct-4

A

Permits cleavage to proceed to 2-Cell stage

47
Q

State role of Nanog, what produces it?

A

Maintains ICM integrity

Produced by ICM in late morula stage

Without nanog = ICM differentiates into endoderm

Without Oct-4 = ICM differentiates into trophoblast

48
Q

State the role of Sox2

A

Helps control regulation of genes involved in differentiation

First expressed in 8-cell stage

49
Q

Define Bateson’s rule

A

Duplicated structures are joined during critical developmental stages

Mirror Images

50
Q

Functions of ZP

A
  • Promotes oocyte & follicle maturation
  • Barrier
  • Initiates acrosomal reaction
  • Prevents polyspermy
  • Acts as a porous filter where certain substances can reach the embryo
  • Immunological barrier b/w mother & embryo
  • Facilitates trophoblast cell differentiation
  • Prevents premature implantation of embryo
51
Q

What is the most common condition associated with spontaneously aborted embryos?

Maternal imprinting

Paternal imprinting

Ectopic pregnancy

Chromosomal abnormalities

Lack of X-chromosomeal inactivation

A

Chromosomal abnormalities

52
Q

What tissue from the implanting embryo directly interfaces with the endometrial connective tissue?

Corona radiata

Inner cell mass

Extraembryonic mesoderm

Epiblast

Syncytiotrophoblast

A

Syncytiotrophoblast

53
Q

Which of the following tissues arises from cells passing through the primitive streak?

Embryonic endoderm

Hypoblast

Cytotrophoblast

Primary yolk sac

Amnion

A

Embryonic endoderm

54
Q

Identical twinning is made possible by what process or property of the early embryo?

Regulation

Aneuploidy

Paternal imprinting

Maternal imprinting

X-chromosomal inactivation

A

Regulation

55
Q

The Zone pellucida:

Aids in penetration of the endometrial epithelium

Serves as a source of nutrients for the embryo

Prevents premature implantation of the cleaving embryo

All of the above

None of the above

A

Prevents premature implantation of the cleaving embryo

56
Q

The prechordal plate plays an important role in regionalization of the:

Notochord

Forebrain

Embryonic mesoderm

Primitive node

Hindbrain

A

Forebrain

KCUMB Embryology (4 decks)

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