HUMAN REPRODUCTION

MALE REPRODUCTIVE ORGANS

TESTIS-

250 compartments- testicular lobules

Seminiferous tubules- male germ cells + sertoli cells

Interstitial cells of leydig

ACCESSORY DUCTS

RETE TESTIS

VASA EFFERENTIA- leaves the testis

EPIDIDYMIS

VAS DEFERENS

EJACULATORY DUCTS

URETHRA

ACCESSORY GLANDS

Seminal vesicle

Prostate

Bulbourethral glands 

SEMINAL PLASMA- Fructose, calcium, enzymes

EXTERNAL GENITALIA- PENIS

corpus cavernosum

Glans, foreskin

FEMALE REPRODUCTIVE ORGANS

Pelvic region

OVARY 2-4cm length

Epithelium+ stroma

Stroma= cortex + medulla

DUCTS 

OVIDUCT

UTERUS

CERVIX

VAGINA

GLANDS

EXTERNAL GENITALIA

MONS PUBIS

LABIA MAJORA

LABIA MINORA

CLITORIS

MAMMARY GLANDS

• Paired structures - glandular tissues and fats, the amount of fat varies from person to person.
• The glandular tissue of each breast is divided into 15-20 mammary lobes
• alveoli secrete milk, which is stored in lumens of alveoli.
• The alveoli open into mammary tubules and the tubules of each lobe join to form a mammary duct which joins to form a wider mammary ampulla.
• Mammary ampulla is connected to lactiferous duct through which milk is sucked out.

GAMETOGENESIS

SPERMATOGENESIS

SPERMS

OOGENESIS

MENSTRUAL CYCLE

The reproductive cycle in the female primates.

The first menstruation which begins at puberty - menarche .

 The cycle is repeated at an interval of 28-29 days. 

Menstrual cycle involve three phases- menstrual phase, follicular phase and luteal phase.

Menstrual phase-

• Menstrual flow occurs and lasts for about 3-5 days.
• The endometrial lining of the uterus breaks along with the blood vessels which forms a red fluid and results in menstrual flow.
• If the ovum is fertilized by a sperm menstrual flow does not occur and hence indicates pregnancy.

Follicular phase-

• In this phase, the primary follicles -- grow --  fully matured graafian follicle.
• Endometrium regenerates
• Changes in Pituitary hormone and ovarian hormones induce the formation of graafian follicle and regeneration of endometrium.
• The secretion of gonadotropins like luteinizing hormone (LH) and follicular stimulating hormone(FSH) increases gradually during this phase and stimulates follicular development as well as secretion of estrogens by the growing follicles.
• Both LH and FSH attain a peak level in the middle of cycle about 14th day.
• Rapid secretion of LH leading to its maximum level during the mid-cycle called LH surge induces rupture of Graafian follicle and thereby the release of ovum known as ovulation.

Luteal phase-

• ruptured part of Graafian follicle transforms into yellow body- Corpus luteum.
• The corpus luteum secretes progesterone hormone which maintains the endometrium for implantation of the fertilized ovum.
• During pregnancy- all events of the menstrual cycle stop-- no menstruation.
• In the absence of fertilization--the corpus luteum degenerates-- disintegration of the endometrium-- menstruation and a new cycle begins.

 In human beings, menstrual cycles ceases around 50 years of age and known as menopause.

FERTILIZATION

• The fusion of haploid male gamete, sperm and haploid female gamete, ovum.
• During coitus, sperm is released by male partner into the vagina of the female partner -- insemination
• The motile sperms swim and pass the cervix -- uterus -- ampullary-isthmic junction-- ovum --- FERTILIZATION

• All copulations do not lead to fertilization because fertilization can only occur if the ovum and sperms are transported simultaneously to the ampulla-isthmic junction.
• The sperm comes in contact with zona-pellucida layer of the ovum --ovum blocks the entry of the additional sperms thus only one sperm fertilizes the ovum.

• The secretions of acrosome help the sperm to enter into the ovum through zona pellucida and the plasma membrane.
• secondary oocyte completes meiosis II and results in the formation of a second polar body and haploid ovum.
• The haploid nucleus of the sperm and ovum fuse together to form a zygote.

CLEAVAGE

• mitotic division - as the zygote moves through the isthmus towards the uterus and forms 2, 4, 8, 16 daughter cells -- blastomeres
• The embryo with 8 to 16 blastomeres - morula
• morula- further division- blastocyst - in the uterus
• The blastomeres in the blastocyst are arranged- 1. an outer layer- trophoblast.  2. inner mass of cells -inner cell mass.

• The trophoblast layer --attached to the endometrium of the uterus
•  the inner cell mass divide to cover the blastocyst hence blastocyst becomes embedded in the endometrium of the uterus --implantation.

PREGNANCY AND EMBRYONIC DEVELOPMENT

• After implantation, finger like projections appear on the trophoblast called as chorionic villi.

• Uterine tissue and maternal blood surrounds the chorionic villi.
• The chorionic villi and uterine tissue together form a structural and functional organic structure between developing embryo and tissues of the mother called as placenta

Functions of placenta-

• The placenta facilitates the supply of oxygen and nutrients to the embryo.
• Help in the removal of carbon dioxide and excretory/waste materials produced by the embryo

• The placenta is connected to the embryo through an umbilical cord which helps in the transport of substances to and from the embryo.
• Placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG),human placental lactogen (hPL),estrogens, progestogen. etc.

• A hormone called relaxin is secreted by the ovary in the later phase of pregnancy.
• hCG, hPL and relaxin are produced in women only during pregnancy.
• Levels of other hormones like estrogens, progestogens, cortisol, prolactin, thyroxine, etc., are increased several folds in the maternal blood.
• Increased production of all the hormones is essential for supporting the fetal growth, metabolic changes in the mother and maintenance of pregnancy.

• After implantation, the inner cell mass is differentiated into outer layer called ectoderm and an inner layer called endoderm with a middle Mesoderm.

• Three layers give rise to all organs in adults.

• The cells which have the potency to give rise to any types of cells in the body are called stem cells.
• The human pregnancy lasts for 9 months- gestational period
•  heart develops after one month of pregnancy, limbs develop by the end of second month,major organ systems are formed by the end of 3 months.
• First movement and appearance of hairs are during fifth month of pregnancy.
• By the end of 24 weeks, the body covers with fine hair, eye-lids separate, eyelashes form.
• By the end on nine month, the fetus fully develops.