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Myometrium

The thick muscular layer of the uterus that contracts during childbirth and menstruation.

Follicle-stimulating hormone (FSH)

A hormone that stimulates oocyte maturation and follicular development in the ovaries.

Luteinizing hormone (LH)

A hormone that works alongside FSH to stimulate oocyte maturation in the ovaries.

Testosterone

A hormone that regulates sperm production by acting on Sertoli cells.

Sertoli cells

Cells that support and nourish developing sperm cells in the testes.

Myoid cells

Smooth muscle-like cells surrounding seminiferous tubules that help move sperm and testicular fluid.

Pampiniform plexus

A network of veins that absorbs heat from the arterial blood supply to keep the testes cool.

Spermatic cord

A structure in males that contains the vas deferens, blood vessels, and nerves, passing through the inguinal canal.

Round ligament of the uterus

A structure in females that passes through the inguinal canal.

Spongy (penile) urethra

The longest portion of the male urethra, running through the penis to the external urethral orifice.

Vasectomy

A surgical procedure that cuts and seals the vas deferens to prevent sperm from mixing with semen.

Somatic cells

Cells that reproduce via mitosis, resulting in two identical diploid daughter cells.

Sex cells (gametes)

Cells produced through meiosis, resulting in four haploid cells with genetic diversity.

Oocytes

Female gametes produced in the ovaries that undergo maturation during the menstrual cycle.

Human somatic karyotype

Consists of 46 chromosomes (23 pairs).

Germline karyotype

Consists of 23 chromosomes (haploid), as found in gametes.

Fertilization

The process that results in the formation of a diploid zygote containing genetic material from both parents.

Birth ratio in the U.S.

Approximately 105 boys are born for every 100 girls.

Birth ratio in China and India

Can be as high as 110-120 boys for every 100 girls due to cultural preferences.

Identical twins

Twins that result from the splitting of a single fertilized egg into two embryos (monozygotic twins).

Conjoined twins

Twins that are physically connected at birth due to incomplete division of the zygote.

True genetic chimeras

Individuals with two genetically distinct cell lines arising from the fusion of two embryos.

FSH in spermatogenesis

Regulates spermatogenesis by stimulating Sertoli cells and influencing Leydig cells to produce testosterone.

Primary spermatocytes

Cells that undergo meiosis I to form two secondary spermatocytes.

Spermatogonium maturation time

Takes approximately 64 to 72 days to mature into spermatozoon.

Leydig cells

Cells that produce testosterone in response to luteinizing hormone (LH) and stimulate spermatogenesis.

Acrosome of spermatozoon

Formed by the Golgi apparatus, containing enzymes for penetrating the oocyte during fertilization.

Primary oocytes

Present in a female newborn's ovary, arrested in prophase I of meiosis until puberty.

Granulosa cells

Cells that surround the developing oocyte and secrete the zona pellucida, crucial for sperm binding.

Oogenesis

The process that occurs in the ovaries where oocytes develop through several stages during the menstrual cycle.