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Meiosis

A special type of nuclear division that produces gametes, involving one round of DNA replication followed by two rounds of nuclear division, resulting in four haploid daughter cells.

Gametes

Reproductive cells (sperm and ova) that have half the original number of chromosomes (23 in humans) and are produced through meiosis.

Haploid

A cell that contains only one complete set of chromosomes, represented as 'n', which for humans is 23 chromosomes.

Diploid

A cell that contains two complete sets of chromosomes, represented as '2n', which for humans is 46 chromosomes.

Crossing Over

The exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I of meiosis, resulting in genetic recombination.

Independent Assortment

The random distribution of homologous chromosomes to gametes during metaphase I of meiosis, contributing to genetic diversity.

Non-disjunction

The failure of homologous chromosomes or sister chromatids to separate properly during cell division, leading to gametes with abnormal chromosome numbers.

Stem Cells

Undifferentiated cells capable of self-renewal and differentiation into specialized cell types, serving as reservoirs for tissue growth, repair, and regeneration.

Totipotent Stem Cells

Stem cells that can differentiate into any cell type, including all cell types of the embryo and extra-embryonic tissue. Found in the earliest stages of development.

Pluripotent Stem Cells

Stem cells that can differentiate into almost any cell type, but not extra-embryonic tissues. Found in the inner cell mass of the blastocyst.

Multipotent Stem Cells

Stem cells that can differentiate into a limited range of cell types, usually specific to a particular tissue. Found in various adult tissues.

Cancer

A disease caused by uncontrolled cell division due to accumulated mutations, disrupting normal tissue function and potentially leading to tumor formation.

Tumor

A mass of abnormal cells formed from uncontrolled cell growth, categorized as benign (non-invasive) or malignant (invasive and capable of spreading).

Malignant Tumor

A type of tumor that invades surrounding tissues and has the capacity to metastasize, spreading cancer cells to other bodily regions.

Benign Tumor

A non-cancerous tumor that does not invade surrounding tissues or spread to other body parts.

Apoptosis

Programmed cell death that occurs in a normal and controlled manner, which is different from necrosis, an uncontrolled cell death.

Placenta

An organ that develops during pregnancy, providing oxygen and nutrients to the developing fetus and removing waste products.

Embryonic Germ Layers

Three layers (ectoderm, mesoderm, endoderm) that develop from the inner cell mass of the blastocyst and differentiate into various tissues and organs.

Ectoderm

The outermost embryonic germ layer that develops into the skin, hair, nails, and nervous system.

Mesoderm

The middle embryonic germ layer that develops into muscle, bone, the circulatory system, and other connective tissues.

Endoderm

The innermost embryonic germ layer that develops into the lining of the digestive tract, lungs, and other internal organs.

Zygote

The fertilized ovum formed by the union of sperm and egg, which divides to form a morula and subsequently a blastocyst.

Blastocyst

A hollow ball of cells that forms about six days after fertilization, composed of an outer trophoblast and an inner cell mass that will develop into the embryo.

Oogenesis

The process of female gamete (ova) production, which begins before birth and is characterized by unequal cytokinesis, producing one functional ovum and polar bodies.

Spermatogenesis

The process of male gamete (sperm) production, which occurs continuously post-puberty and results in four functional sperm from each primary spermatocyte.

Oxytocin

A hormone released during labor that stimulates uterine contractions and helps coordinate the childbirth process.

First Stage of Labour

Dilation stage, where contractions increase in frequency and intensity, leading to complete dilation of the cervix to 10 cm.

Second Stage of Labour

Expulsion stage, beginning with full dilation of the cervix and ending with the birth of the fetus.

Third Stage of Labour

Delivery of the placenta, where contractions continue to expel the placenta and other membranes following the birth of the baby.

Cervical Screening Test

A medical test used to detect abnormal cells in the cervix and related conditions, facilitating early detection of cervical cancer.

Primary Follicle

The stage of ovarian follicles that contains a primary oocyte surrounded by granulosa cells, which provide nourishment.

Granulosa Cells

Supportive cells that surround the oocyte in the ovarian follicles, providing nutrients and playing a role in the maturation process.

Luteinising Hormone (LH)

A hormone involved in regulating the menstrual cycle and ovulation; it triggers the release of a mature ovum at ovulation.

Follicle-Stimulating Hormone (FSH)

A hormone that stimulates ovarian follicle development and promotes estrogen production, playing a key role in the menstrual cycle and ovarian function.

In vitro Fertilization (IVF)

A reproductive technology that involves fertilizing an egg with sperm outside the body and then implanting the resulting embryo into the uterus.

Amniotic Fluid

The fluid that surrounds and cushions the developing fetus in the amniotic sac, providing protection, temperature regulation, and space for fetal movement.

Acrosome

A cap-like structure over the head of a sperm cell that contains enzymes necessary for penetrating the outer layer of an ovum during fertilization.

Umbilical Cord

The structure that connects the developing fetus to the placenta, carrying nutrients and oxygen to the fetus and removing waste products.

hCG (human Chorionic Gonadotropin)

A hormone secreted by the blastocyst and later the placenta, which supports the corpus luteum and maintains the endometrial lining during early pregnancy.

The Corpus Luteum

A temporary endocrine structure involved in the menstrual cycle and early pregnancy, producing progesterone and helping maintain the endometrium.

Prophase I

A stage in meiosis where homologous chromosomes pair up and crossing over occurs, exchanging genetic information.

Anaphase I

A stage in meiosis where homologous chromosomes are pulled apart to opposite poles of the cell.

Telophase II

The final stage of meiosis II, where individual chromatids reach the poles, and the cell divides to form haploid gametes.

Chiasma

The site of crossing over and exchange of genetic material between non-sister chromatids.

Spermatid

A haploid cell resulting from meiosis II in spermatogenesis, which matures into a spermatozoon.

Secondary oocyte

The haploid cell produced after the first meiotic division in oogenesis, which is released during ovulation.

Menopause

The natural cessation of the menstrual cycle in women, marking the end of reproductive capability, typically occurring between ages 45-60.

Embryoblast

The inner cell mass of a blastocyst that develops into the embryo.

Trophoblast

The outer layer of cells of the blastocyst that forms the placenta.

Cervical Canal

The passage leading from the uterus to the vagina, used during labor for the passage of the fetus.

Fertilization

The process in which sperm and egg cells unite to form a zygote, marking the beginning of a new organism's development.

Totipotent Cells

Cells that can give rise to any cell type, including a complete embryo and supportive extra-embryonic tissues.