Oogenesis

Question 1

What is the function of fimbriae?

Answer 1

The fimbriae connect the ovaries to the opening of the fallopian tubes, creating a funnel-shaped space for the ovum to travel through.

Question 2

What is the most common site of fertilisation?

Answer 2

Ampulla: The major channel in the fallopian tube, located in-between the infundibulum and the isthmus.

Question 3

What is a morula?

Answer 3

A solid mass of blastomeres resulting from a number of cleavages of a zygote, or fertilized egg.

Question 4

True or False -

One quality ovum is released every month.

Answer 4

True

Question 5

True or False -

Ovulation is regulated by the hypothalamus and triggered by the release of GnRH by the medial preoptic area

Answer 5

True

Question 6

True or False -

Primordial germ cells are cells that give rise to germ cells in the gonads from which the gametes are ultimately derived

Answer 6

True

Question 7

True or False -

Primordial germ cells are diploid (2N), 46 chromosomes

Answer 7

True

Question 8

What happens to oogonia?

Answer 8

Oogonia undergo proliferation via mitosis into primary oocytes within the primary follicles. Starts in week 4 and present in foetus until week 30.

Question 9

What are primary oocytes?

Answer 9

From week 30 of development, primary oocytes remain dictyate (progress until prophase I) until puberty. Once puberty occurs, some primary oocytes periodically resume meiosis becoming secondary oocytes.

Question 10

What are primary oocytes?

Answer 10

From week 30 of development, primary oocytes remain dictyate (progress until prophase I) until puberty. Once puberty occurs, some primary oocytes periodically resume meiosis becoming secondary oocytes.

Question 11

Describe primordial follical.

Answer 11

A primordial follicle is a structure enveloping a small primary oocyte within a single layer of squamous granulosa cells on the basal lamina.

Question 12

What are primary follicles?

Answer 12

A primary follicle is defined by the presence of cuboidal granulosa cells surrounding an oocyte which produce estrogen. Also contain theca interna cells that produce LHR.

Question 13

True or False -

Theca interna cells differentiate into theca lutein cells (retained as the corpus luteum) and help in the production of estrogen by supplying granulosa cells androgens for the conversion into estrogen.

Answer 13

True

Question 14

True or False -

Once estrogen reaches a certain level indicating a mature follicle and egg, the brain releases a surge of LH to rupture the follicle and trigger it to release the egg.

Answer 14

True

Question 15

What is the zone of pellucida?

Answer 15

The zona pellucida (extracellular matrix) supports communication between oocytes and follicle cells during oogenesis; protects oocytes, eggs, and embryos during development, and regulates interactions between ovulated eggs and free-swimming sperm during and following fertilization.

Question 16

What is the function of the corpus luteum?

Answer 16

The function of the corpus luteum is secretion of progesterone, which is required for maintenance of normal pregnancy in mammals. The corpus luteum develops from residual follicular granulosal and thecal cells after ovulation.

Question 17

What is the function of the corpus luteum?

Answer 17

The function of the corpus luteum is secretion of progesterone, which is required for maintenance of normal pregnancy in mammals. The corpus luteum develops from residual follicular granulosal and thecal cells after ovulation.

Question 18

What is an ootid?

Answer 18

An ootid is a mature ovum after penetration by sperm but before the formation of a zygote.

Question 19

What is compaction in fertilization?

Answer 19

After fertilization and during embryogenesis, the one-cell embryo undergoes a series of cleavage divisions progressing from two cells and up to more than eight cells. At a certain point, the blastomeres begin to form tight and gap junctions in a process known as compaction, which enables intercellular communication.

Question 20

What is a trophoblast?

Answer 20

Trophoblasts are cells forming the outer layer of a blastocyst, which provides nutrients to the embryo, and develops into the placenta. They are formed during the first stage of pregnancy and are the first cells to differentiate from the fertilized egg.

Question 21

What produces human chorionic gonadotropin (hCG)?

Answer 21

Human chorionic gonadotropin is produced by syncytiotrophoblastic cells of the placenta during pregnancy. The hormone stimulates the corpus luteum to produce progesterone to maintain the pregnancy.