lab exam 4 sperm, oogenesis, spermatogensis, cell division and reproduction

Where are sperm cells produced?

In the seminiferous tubules of the testes through spermatogenesis. These tubules are lined with germ cells and supported by Sertoli cells.

What is the first structure sperm enter after being produced?

The rete testis, a network that collects sperm from seminiferous tubules.

What is the pathway sperm take from the rete testis?

Seminiferous tubules → Rete testis → Efferent ductules → Epididymis

What is the function of the epididymis?

Site of sperm maturation

Sperm gain motility and fertilization capability

Storage until ejaculation

What structure transports sperm from the epididymis?

The function of ductus (vas) deferens

What happens when sperm reach the end of the vas deferens?

It joins with the duct of the seminal vesicle to form the ejaculatory duct

Where do ejaculatory ducts empty?

Into the prostatic urethra

Final pathway of sperm to exit the body?

Prostatic urethra → Membranous urethra → Spongy (penile) urethra → External urethral orifice

Full sperm pathway

Seminiferous tubules → Rete testis → Efferent ductules → Epididymis → Vas deferens → Ejaculatory duct → Urethra → Outside

What is semen?

A mixture of sperm cells + secretions from accessory glands that supports, nourishes, and transports sperm.

What percentage of semen is sperm?

Only about 1–5% (most is glandular secretions)

What do seminal vesicles contribute to semen?

~60–70% of semen

Fructose (energy for sperm)

Prostaglandins (stimulate uterine contractions)

Alkaline fluid (neutralizes acidity)

What does the prostate gland contribute?

~25–30% of semen

Milky fluid

Enzymes (e.g., PSA)

Helps activate sperm

What do bulbourethral (Cowper’s) glands secrete?

Mucus-like fluid

Lubricates urethra

Neutralizes acidic urine residue

What organs are involved in semen production?

Testes (sperm)

Seminal vesicles

Prostate gland

Bulbourethral glands

What is the exocrine product of the testes?

Sperm cells

Which cells produce sperm?

Spermatogenic cells in seminiferous tubules

What is the endocrine product of the testes?

Testosterone

Which cells produce testosterone?

Interstitial (Leydig) cells

What do Sertoli cells secrete

Inhibin → regulates FSH

Androgen-binding protein (supports spermatogenesis)

What is the exocrine product of the ovaries?

Oocytes (eggs)

What is the endocrine function of the ovaries?

Secretion of sex hormones

What hormones do ovaries produce?

Estrogens

Progesterone

Which ovarian structure produces estrogen?

Developing follicles (granulosa cells)

Which structure produces progesterone?

Corpus luteum

What is inhibin in females and where is it produced?

Hormone that inhibits FSH

Produced by granulosa cells

What is oogenesis?

The process by which female gametes (eggs) are produced in the ovaries, involving meiosis and unequal cytokinesis.

What are oogonia?

The primordial germ cells in the female reproductive system that develop into oocytes during oogenesis.

What is a primary oocyte?

an immature female gamete that has begun the first meiotic division but is arrested in prophase I until puberty, when it resumes meiosis.

When does a primary oocyte resume development?

At puberty, during each ovarian cycle (stimulated by hormones)

What happens when a primary oocyte completes meiosis I?

It forms:

Secondary oocyte (n)

First polar body (n)

What is a secondary oocyte?

A mature female gamete that is produced from a primary oocyte during meiosis. It is released during ovulation and will complete meiosis II only if fertilized.

What is a polar body?

A small haploid cell that is a byproduct of oocyte division during meiosis, which typically does not participate in fertilization.

When does meiosis II complete?

Only if fertilization occurs

What is an ovum?

A mature female gamete resulting from the division of a secondary oocyte after fertilization, which can be fertilized by a sperm cell.

oogenesis stages

Oogonia → Primary oocyte → Secondary oocyte → Ovum

What are the three phases of the ovarian cycle?

Follicular phase

Ovulation

Luteal phase

What happens during the follicular phase?

Follicles develop

Primary oocyte matures

Estrogen levels rise

What triggers ovulation?

A surge in luteinizing hormone (LH)

What is released during ovulation?

The secondary oocyte

What happens during the luteal phase?

Follicle becomes corpus luteum

Secretes progesterone

Prepares uterus for implantation

What are the phases of the uterine cycle?

Menstrual phase

Proliferative phase

Secretory phase

What happens during the menstrual phase?

Shedding of functional layer of endometrium

Caused by drop in estrogen & progesterone

What happens during the proliferative phase?

Endometrium rebuilds

Stimulated by estrogen

Occurs alongside follicular phase

What happens during the secretory phase?

Endometrium thickens and becomes glandular

Stimulated by progesterone

Prepares for implantation

Which hormones regulate the female cycle?

FSH (follicle-stimulating hormone)

LH (luteinizing hormone)

Estrogen

Progesterone

What does FSH do?

Stimulates follicle development in ovaries

What is the role of estrogen?

ebuilds endometrium

Causes LH surge (positive feedback)

What is the role of progesterone?

Maintains uterine lining

Prepares uterus for pregnancy

What happens if fertilization does NOT occur?

Corpus luteum degenerates

Progesterone & estrogen drop

Menstruation begins

What happens if fertilization DOES occur?

Embryo produces hCG

Corpus luteum maintained

Progesterone remains high

No menstruation

What is spermatogenesis?

The process of producing male gametes (spermatozoa) from stem cells in the seminiferous tubules of the testes through mitosis, meiosis, and differentiation.

Where specifically does spermatogenesis occur?

In the seminiferous tubules of the testes.

What is the overall progression of spermatogenesis?

Spermatogonia → Primary spermatocyte → Secondary spermatocyte → Spermatids → Spermatozoa

What are spermatogonia?

The initial precursor cells in spermatogenesis, found in the seminiferous tubules, that undergo mitosis to produce primary spermatocytes.

What is a primary spermatocyte?

A diploid cell that undergoes meiosis I during spermatogenesis to form two secondary spermatocytes.

What are secondary spermatocytes?

Haploid cells resulting from the first meiotic division of primary spermatocytes, which go on to undergo meiosis II to produce 4 spermatids.

What are spermatids?

immature sperm cells, Haploid cells that result from the second meiotic division of secondary spermatocytes, eventually developing into mature spermatozoa.

What is spermiogenesis?

The final stage of spermatogenesis, where spermatids undergo morphological changes, transforming into mature spermatozoa.

What are spermatozoa?

Mature male reproductive cells that are motile and capable of fertilizing an oocyte.

What major changes occur during spermiogenesis?

During spermiogenesis, spermatids undergo condensation of the nucleus, development of the acrosome, and formation of the flagellum, transforming into streamlined, motile spermatozoa.

What is the role of Sertoli cells?

Support and nourish developing sperm

Form blood-testis barrier

Secrete inhibin

Help with spermiogenesis

What hormones regulate spermatogenesis?

FSH → stimulates Sertoli cells

LH → stimulates Leydig cells → testosterone

Testosterone → essential for sperm production

Where do sperm gain motility?

In the epididymis (not in seminiferous tubules)

What is meiosis?

cel division that lowers chromosome numbers by half to make haploids in the gonads - starts with 1 diploid > ends with 4 haploids- includes meiosis 1 and 2

purpose of meiosis

genetic diversity + maintain chromosome number across generations.

What is the difference between Meiosis I and Meiosis II?

omologous chromosomes separate

Reduces chromosome number : Sister chromatids separate

Similar to mitosis

What is gametogenesis?

process of producing mature sex cells (gametes) through meiosis and maturation.

Where does gametogenesis occur?

Testes → sperm production

Ovaries → egg production

What is unique about spermatogenesis?

Begins at puberty

Continues throughout life

Produces four functional sperm from each primary spermatocyte

Equal cell division

What is synapsis?

The pairing of homologous chromosomes during prophase I of meiosis.

Examples of diploid cells?

• Skin cells

• Muscle cells

• Stem cells

• Zygote

What is a zygote?

The fertilized egg formed when a sperm and egg unite.

Why is the zygote important?

It is the first cell of a new individual and begins embryonic development.