Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Glossary of Reptile Reproduction Terms

Melissa Kaplan, 2000


The following terms are generally applicable to reproduction in general of viviparous, oviparious and ovoviviparous species.

Special note: Some female reptiles, most notably green iguanas, do not need the presence of a male of their species to launch into and complete their reproductive cycle (vitellogenesis through laying of the mature infertile eggs), while others do need the presence of one or more males, and perhaps copulation, to stimulate the hormone and other changes that lead to egg maturtion and laying. To confound matters still further, some female reptiles, especially chelonains, can retain sperm for many years before finally laying a fertilized egg.


The number of eggs laid; egg production and laying. (1. The females of some species clutch several times a year. 2. The average clutch size of adult green iguanas is 50-70 eggs.)


Individuals who hatched from the same clutch of eggs.


Housing males and females together.

cycle; cycling

The recurring reproductive phase, triggered by hormonal changes triggered by environmental cues. May occur on an annual basis, or a more or less frequent basis.


The estrogen hormon primarily responsible for stimulating yolk synthesis in females.


When a sperm from a male penetrates the ova of a female. In oviparous species, fertilization occurs when the sperm meet the ova as they pass through the oviduct, a passage which also layers the outside of the egg with calcium to form a shell.


1. A small bodily cavity or sac; any small spherical group of cells containing a cavity. pl. follicles. 2. small egg-containing sacks found in the female ovary. In fertile human females, one follicle will become dominant and release a mature egg (ovulate) during every cycle. In oviparous reptile species, several mature eggs will be produced, depending on the species and the individual.

follicular vitellogenesis

The development of the yolk in the eggs.

in vitro

Occurring, or made to occur, outside of a living organism or natural setting (i.e, "test tube babies" are when the egg and sperm have been combined and fertilization occurs in the lab and then implanted into the mother or surrogate).

in vivo

Occurring, or made to occur, within a living organism or natural setting.


The act of copulation, during which the male transfers his sperm into the female. .


The burrow or pallet dug by the female in which to deposit her eggs.


An egg before maturation (oogenesis).


The formation and maturation of an egg.


Eggs. sing. ovum The mature ova are 10-100 times the size of inactive (pre-vitellogenic) ova. An ovum technically becomes an egg once the albumin and shell are added as they pass through the oviduct into to coelomic cavity.


The female gonad, producing eggs and female hormones. The ovary varies in appearance and size depending on the stage of oogenesis. An inactive ovary may appear as a small smear of caviar-looking substance, while an active ovary looks like a mass of white spheres (the developing eggs) held together by transparent membranes laced with blood vessels.

ovarian ducts

var. oviduct. Secrete albumin as well as shelling the eggs.


Surgical removal of one or both ovaries.


Surgical removal of the ovary and uterine tube (oviduct).


Egg-laying. (Anoles are oviparous.)


Retains unshelled eggs until ready to hatch; young appear as if by viviparity. (Some skink species are ovovivparous.)


The laying of eggs.


The hollow tube through which some insects (such as crickets) and chelicerata, lay their eggs. In bees and wasps, this has been modified into the stinger.


To lay or discharge eggs, especially as applied to organisms with a specialized egg-laying structure, such as an ovipositor.


An estrogen antagonist, this steroid hormone produced in the ovary. In uterine mammals, it prepares the uterine lining for the implantation of a fertilized egg.


Named for the prostrate gland where these hormone-like chemicals were first discovered, prostaglandins play a varied role in both males and females.


Some female animals can resorb fully developed eggs. What causes resorbtion in female reptiles is not known, so there is no known way to trigger nor prevent it.

shell calcification

The eggs of oviparous reptile are shelled as they pass through the oviducts on their way to the coelomic cavity, which occurs several days prior to laying. The amount of calcification (thickness, rigidity) varies from species to species. The amount of shelling can be adversely affected due to metabolic bone disease caused by pre-exisiting dietary or environmental deficiencies, or gestational/gravidity-induced MBD when gravid females have not received supplemental calcium to prepare them for the increased calcium demands on their bodies to produce eggs and shells.


An infertile egg.


The development of the egg yolk in the follicles, started when estrogen stimulates the liver to start converting lipids from the body's fat stores, creating vitellogenin. During this time, the liver is enlarged and yellowish-looking.

vitellogenic activity

The development and deposition of yolk.


A protein, synthesized in the liver after estogen stimulation, that is the precursor to several yolk proteins. The maturing follicles absorb vitellogenin from the bloodstream.


Live-bearing. (Many viperid species are viviparous.)

yolk deposition

The deposit of yolk into the ova.

yolk synthesis

The development of yolk, initially started in the liver, complete in the ova.

















































A bit of trivia...
Iguana testes comprise 1% the male iguana's body mass. By comparison, the great apes have testes ranging in size from 0.017% to 0.269%. The great apes, then, have one-fourth as much testicular tissue, relatively speaking, as do the green iguanas. (Human males come in somewhere in the great apes range, with a 6' 0" 180 pound human male having testes weighing in at about 0.041% of body weight.) Iguana keepers who have had occasion to clean up iguana ejaculate are not surprised by this datum. Melissa Kaplan, Iguanas For Dummies (Hungry Minds, Inc., 2000)








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