Latin for "lakes": one lacuna, two lacunae. Refers particularly to spaces that form within the syncytiotrophoblast (which therefore continues to line the spaces), separating the SCT into strips of land and little peninsulas that will develop into chorionic villi, as the lakes coalesce into one large intervillous space, into which maternal arteries will open, delivering blood to the placenta as it is being formed.

A "minimally invasive" surgical operation at which instruments are passed through the wall of the abdomen: (1) for the diagnosis of abnormalities of the abdominal or pelvic organs (such as the fallopian tubes, ovaries and uterus) and to diagnose endometriosis; or (2) therapeutically, to reach the fallopian tubes for certain assisted conception procedures (see gamete intrafallopian transfer and zygote intrafallopian transfer). Carries the risks of surgery (damage to internal organs, hemorrhage, infection) and the risks of general anesthesia.

A surgical operation in which the abdomen is opened. Needed for microsurgery operations on the fallopian tubes (although some operations formerly done only at laparotomy are now possible at laparoscopy). For infertility surgery, the scar from a laparotomy is usually a low, horizontal one, just above the pubic bone. Several days in hospital are needed; most people are off work about 3 weeks; and some numbness or sensitivity below the scar can be expected for several months, as nerves to the skin regrow.

The colon.

(LMP) The normal period immediately preceding conception. For convenience, obstetricians calculate the duration of a pregnancy as starting with this date, even though of course it does not truly begin until fertilisation (or, some would say, implantation).

A GnRH agonist made by Abbott and sold as Lupron in the US. Called leuprorelin in Australia and Europe, and sold there as Lucrin. Administered by daily injection under the skin or as a depot preparation once per month.

Cells of the testis lying between the testicular tubules in which sperm are formed (hence their other name, interstitial cells), and responsible for the production of the male sex hormone testosterone under the influence of luteinising hormone.

A sudden and huge increase in production of luteinising hormone by the pituitary gland in response to sustained and substantial levels of estradiol in the blood in women, midway through the ovarian cycle. Causes ovulation about 36 hours after it starts (about 20 hours after its peak). If not suppressed during assisted conception (see GnRH-agonists and GnRH-antagonists) it can start before human chorionic gonadotropin has been given, so spoiling the timing of egg retrieval. Timely production of the LH surge in adult women depends on female conditioning of the hypothalamus and/or the pituitary gland before birth. Detectable by testing the urine with a special kit.

Read chromosomal cross-over first, then come back. Because it can take lots of cross-overs (i.e. lots of generations) to send two genes that live as neighbours on a chromosome into different directions (i.e. they end up in different people), we can do family studies to work out how closely people are related by seeing how long the runs are of identical genes.

A treatment protocol for using GnRH-agonists that involves their use for more than a week before injections of follicle stimulating hormone (FSH) start for induction of superovulation in assisted conception programs. The advantage is that any temporary rise in luteinising hormone levels and progesterone levels has dissipated before the development is under way of those ovarian follicles from which eggs will be obtained at egg retrieval. The disadvantage, compared with the short protocol, is that higher (hence more expensive) doses of GnRH-agonist and FSH are needed. The GnRH can be started with menstruation or during the luteal phase of the previous cycle.

Early experience with superovulation for in vitro fertilisation, particularly at the original US program in Norfolk VA, saw women patients classified into three classes of responders, depending on how many eggs were obtained at egg retrieval. Poorer than usual outcomes could occur with either a low response or a high response (the high responders generally have polycystic ovaries, with a risk of ovarian hyperstimulation syndrome (OHSS). Many maneuvers have been used to try and retrieve more eggs among low responders, such as starting high dose FSH on day 1, the adding of growth hormone, the avoidance of GnRH-agonists etc., all generally without improving the results. Day 3 serum FSH levels can be high in low responders, indicating a depletion of eggs in the ovaries.

The hollow center of a cylindrical organ or tissue, such as that of a fallopian tube or a blood vessel. Adjective: luminal.

An antibody first noted in the disease systemic lupus erythematosus or 'lupus', that has the ability to stop blood clotting. A cause of recurrent miscarriages. Closely related to a family of anti-phospholipid antibodies, especially anticardiolipin antibody. Also called the lupus inhibitor.

The part of the ovarian cycle between ovulation and the start of a new follicular phase, so dominated by the presence of the corpus luteum and the progesterone it produces. Normally between 11 and 16 days in length. Extended by the action on the corpus luteum of human chorionic gonadotropin (hCG) if implantation of the embryo is successful. Shorter cycles can interfere with implantation (a luteal phase defect). Corresponds with the secretory phase of the menstrual cycle.

(LPD) A luteal phase that is shorter than optimal for a fertilised egg to undergo implantation. Very likely if the luteal phase is shorter than normal (11 to 16 days), but not all luteal phases within this range are innocent. Often caused by a prior defect of the follicular phase or of the development of the ovulating tertiary follicle (the preovulatory follicle) and hence there can be a defect of the egg itself (if ovulation has actually occurred) or there can be a luteinised unruptured follicle -- any of which will either increase the risk of miscarriage or will prevent pregnancy altogether for that cycle. Synonymous with luteal phase insufficiency.

(LUF) Occurs when a reasonably mature tertiary follicle (or preovulatory follicle) receives an LH surge that's enough to make it start producing progesterone, but is not enough to cause it to release its egg through ovulation. The result is that the egg is trapped in the follicle, which to a greater or lesser extent then functions like a corpus luteum, though this stage of the follicle's life is often shorter, giving rise to a luteal phase defect (LPD).

(LH) The hormone, or gonadotropin, produced by the pituitary gland to cause, in women, ovulation of a mature follicle in the ovary, resulting in formation of the corpus luteum; in men, stimulates the production of testosterone by the Leydig cells of the testis. Suppressed by GnRH-agonists and GnRH-antagonists, so that (for ovulation induction) an injection of human chorionic gonadotropin (hCG), which acts the same way, has a predictable time course of action. A small amount of LH is essential for normal function of the tertiary follicle and the corpus luteum. Recombinant LH is under development by Serono as Luveris, but its clinical role in place of hCG is not yet established.

Generic name for recombinant luteinising hormone.

Recombinant luteinising hormone (LH) made by Serono.