S1.7 Reproductive System

What is Gonads

Gonads 性腺 are the primary reproductive organs in humans and other animals.

🔹 Definition:
Gonads are organs that produce gametes (sex cells) and secrete sex hormones.

🔹 Types of gonads:

• Testes (singular: testis) in males

  • Produce sperm (male gametes)

  • Secrete testosterone

• Ovaries in females

  • Produce eggs (ova) (female gametes)

  • Secrete estrogen and progesterone

What is a Gametes

What is the gametes cell in man/women

🔹 Definition:
Gametes are haploid cells (contain half the number of chromosomes compared to normal body cells) that fuse during fertilization to form a zygote.

🔹 Types of gametes:

• Male gamete: Sperm cell

  • Small, motile cell produced by the testes.

• Female gamete: Egg cell (ovum)

  • Large, non-motile cell produced by the ovaries.

🔑 Key points:

• Haploid (n): Contains 23 chromosomes in humans.

• Fertilization: When a sperm (n) and egg (n) combine, they form a zygote (2n) with a full set of chromosomes (46 in humans).

What is a Haploid & Diploid

Haploid refers to a cell that has only one set of chromosomes.

🔹 Definition:
A haploid cell (n) contains half the number of chromosomes found in normal body (somatic) cells.

🔹 In humans:

• Haploid number (n) = 23 chromosomes.

• Found in gametes (sperm and egg cells).

🔹 Why is it important?

• During fertilization, two haploid gametes (sperm and egg) combine to form a diploid (2n) zygote with a complete set of chromosomes (46 in humans).

🔑 Key summary:

• Haploid (n) = 23 chromosomes in humans (sex cells).

• Diploid (2n) = 46 chromosomes in humans (body cells).

Let me know if you want a table comparing haploid, diploid, and p

What are the Accessory organs in the Reproductive system?

1. Glands

2. Ducts

3. External Genitalia

What is a Zygote

A zygote is the first cell formed after fertilization.

🔹 Definition:
A zygote is a diploid cell (2n) formed when a male gamete (sperm) fuses with a female gamete (egg/ovum).

🔹 Key points:

• Contains a full set of chromosomes (46 in humans), half from the father (sperm) and half from the mother (egg).

• It is the beginning of a new organism.

• Undergoes rapid cell division (mitosis) to develop into an embryo.

🔑 In simple words:
Sperm + Egg = Zygote, which then grows into an embryo and later a fetus.

Male Reproductive System Anatomy

1. Urethra

• The tube that carries urine and semen out of the body through the penis.

2. Vas deferens

• Transports sperm from the epididymis to the ejaculatory duct during ejaculation.

3. Testes

• Male gonads that produce:

  • Sperm (spermatogenesis)

  • Testosterone (male sex hormone).

4. Scrotum

• Sac of skin that holds and protects the testes, maintaining a temperature slightly cooler than body temperature for sperm production.

5. Penis

• The external organ that delivers sperm into the female reproductive tract and also carries urine out.

6. Ejaculatory duct

• Formed by the joining of vas deferens and seminal vesicle duct; it carries semen to the urethra.

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Testicular internal structures:

Part	Function
Epididymis	Stores and matures sperm before ejaculation.
Rete testis	Network of tubules that collect sperm from seminiferous tubules and channel it to the epididymis.
Seminiferous tubule	Tiny coiled tubes where spermatogenesis (sperm production) occurs.
Septula	Connective tissue walls that divide the testis into lobules.
Lobules	Compartments within the testis containing seminiferous tubules.
Tunica albuginea	Tough fibrous covering (inner) around the testis, giving it structure.
Tunica vaginalis	The outer protective serous membrane covering the testis.

What do each of the Testicular internal structures do?
Epididymis
Rete testis
Seminiferous tubule
Septula
Lobules
Tunica albuginea
Tunica vaginalis

Testicular internal structures:

Part	Function
Epididymis	Stores and matures sperm before ejaculation.
Rete testis	Network of tubules that collect sperm from seminiferous tubules and channel it to the epididymis.
Seminiferous tubule	Tiny coiled tubes where spermatogenesis (sperm production) occurs.
Septula	Connective tissue walls that divide the testis into lobules.
Lobules	Compartments within the testis contain seminiferous tubules.
Tunica albuginea	Tough fibrous covering (inner) around the testis, giving it structure.
Tunica vaginalis	The outer protective serous membrane covers the testis.

Accessory Glands in Male ?

Gland (English)	中文名称 (Chinese)	Function (English)
Seminal glands	精囊	Produce the fluids that will turn into semen (Produces semen) Sperm plays an important role, it enhances sperm mobility and provides a nutrient-rich environment that suppresses the immune response in female body.
Prostate	前列腺	Produces fluid for semen and surrounds the urethra (Activates the sperm)
Bulbourethral gland (Cowper’s gland)	尿道球腺 (库珀腺)	Discharges a component of seminal fluid into the urethra that lubricates the glans penis

Note: Semen does not contain sperm cells. Instead, it is mixed with sperm cell during ejaculation. cells

Female Reproductive system

What do they each do?

Term
Primordial follicle
Primary follicle
Primary oocyte
Developing follicle
Antrum
Mature Graafian follicle
Mature ovum
Discharging follicle
Ovum
Corona radiata

Term	Function
Primordial follicle	The earliest and most immature stage of the follicle; contains a primary oocyte surrounded by a single layer of flat cells.
Primary follicle	Slightly more developed follicle with a primary oocyte and a layer of cuboidal granulosa cells.
Primary oocyte	Immature egg cell arrested in prophase I of meiosis until puberty; present in primordial and primary follicles.
Developing follicle	Intermediate stage of follicular development as granulosa cells multiply and fluid-filled spaces begin to form.
Antrum	The fluid-filled cavity that forms within the follicle as it matures; helps expand the follicle and prepare it for ovulation.
Mature Graafian follicle	A fully developed follicle containing a secondary oocyte, ready to be released during ovulation.
Mature ovum	The egg that is released during ovulation (technically still a secondary oocyte until fertilized).
Discharging follicle	The follicle that is releasing the ovum during ovulation.
Ovum	The female gamete (egg cell) released into the fallopian tube for possible fertilization.
Corona radiata	Layer of cells surrounding the ovum, which provide nutrients and support as it travels through the reproductive tract.

What is Oogenesis

Oogenesis is the development and maturation of the female sex cells (ova) from primordial germ cells through a series of stages including mitosis, meiosis, and cellular differentiation.

What is an oocyte & ovum

An oocyte is an immature female gamete, or egg cell, involved in reproduction. It is the precursor to the mature egg, and it develops within the ovary during the process of oogenesis.

oocyte = immature female gamet

ovum = mature egg

Female Reproductive System Anatomy

Identify the function of each part.

Structure
Ovaries (What hormones do Ovaries produce)
Fallopian Tubes
Uterus (Womb)
Cervix
Vagina

Structure	Function (English)	中文名称 (Chinese)
Ovaries	Oval-shaped glands where eggs (ova) form and hormones estrogen and progesterone are produced.	卵巢 (luǎn cháo)
Fallopian Tubes	Tubes that connect the ovaries to the uterus; site of fertilization.	输卵管 (shū luǎn guǎn)
Uterus (Womb)	Hormone-responsive organ where implantation, gestation 妊娠, menstruation, and labor occur.	子宫 (zǐ gōng)
Cervix	Lower, narrow part of the uterus that connects it to the vagina.	子宫颈 (zǐ gōng jǐng)
Vagina	Muscular canal that connects the uterus to the outside of the body; birth canal and site of sexual intercourse.	阴道 (yīn dào)

What are estrogen and progesterone and what they do?

🔄 Summary Table:

Hormone	Main Role	Cycle Phase	Produced By
Estrogen	Growth of uterine lining, puberty	Follicular phase	Ovaries
Progesterone	Prepares uterus for implantation	Luteal phase (after ovulation)	Corpus luteum (ovary)

雌激素（Estrogen）和孕激素（Progesterone）

🌸 1. Estrogen 🔹 What is it?

Estrogen is a group of hormones (mainly estradiol) that regulate female sexual development and reproductive function.

🔹 Where is it produced?

• Mainly in the ovaries

• Also in the adrenal glands and fat tissue (in small amounts)

🔹 Main Functions:

Function	Description
Sexual development	Triggers the development of secondary sex characteristics (e.g., breasts, wider hips) during puberty.
Menstrual cycle	Thickens the endometrial lining of the uterus during the first half of the cycle.
Bone health	Helps maintain bone density.
Skin and hair	Supports skin elasticity and hair growth.

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🌙 2. Progesterone 🔹 What is it?

Progesterone is a hormone that prepares the body for pregnancy and helps maintain it in early stages.

🔹 Where is it produced?

• Corpus luteum in the ovary (after ovulation)

• Placenta (during pregnancy)

🔹 Main Functions:

Function	Description
Prepares uterus	Maintains and thickens the endometrial lining for potential implantation of a fertilized egg.
Supports pregnancy	Prevents uterine contractions and supports early embryo growth.
Regulates cycle	Works with estrogen to control the second half of the menstrual cycle.

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The anatomy of the Vulva

Structure	Description / Function
Mons Pubis	Area of fatty tissue that covers the pubic bone. “Mons Pubis” 在中文里通常翻译为 阴阜 (yīn fù). 它指的是女性外阴部，耻骨联合前方隆起，呈丘状，由皮肤和脂肪层构成. 青春期后，阴阜上开始长出阴毛，呈倒三角形分布.
Labia Majora	Fleshy folds of tissue (outer/larger lips) that extend from the mons pubis to the perineum.
Labia Minora	Two inner folds of skin (inner/smaller lips) that surround the opening of the vaginal vestibule.
Vestibule 阴道前庭	Space between the labia minora housing the urethral orifice and vaginal orifice.
Urethral Orifice 尿道口	Opening through which urine is discharged from the body.
Vaginal Orifice 阴道口	Slit below and behind the urethra; opening for menstrual flow and childbirth.
Anus	Opening of the rectum; passage for solid waste to exit the body.

How the Endocrine & Reproductive system work together?

sperm and semen difference

Sperm and semen are related but distinct components of male reproductive fluids. Sperm are the individual male reproductive cells, while semen is the fluid that carries and protects sperm. Essentially, sperm are a component of semen.