Surgery – Reproduction and fertilization techniques
Reexamination Certificate
1999-11-30
2004-01-06
Kearney, Rosiland S. (Department: 3739)
Surgery
Reproduction and fertilization techniques
C600S034000, C600S035000, C435S290400
Reexamination Certificate
active
06673008
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to apparatus and methods for the development of an embryo outside the body, and more specifically, to apparatus and methods of providing the optimal environment for embryo development until the embryo is ready for implantation into the body.
BACKGROUND OF THE INVENTION
About every 28 days or so, the post-pubescent female human goes through the reproductive cycle. The cycle is divided into two phases: the follicular phase (generally the first 14 days, or half of the cycle); and the luteal phase (generally the last 14 days, or half of the cycle).
During the follicular phase, the anterior pituitary gland secretes follicle stimulating hormone (FSH), which is a small glycoprotein. The ovaries have a specific receptor cite for the FSH. FSH assists in the development of one or two small cysts (i.e., egg follicles) in the ovaries, each of which contains an ovum. Cells surrounding the developing ovum, in turn, produce estrogen. Estrogen has several effects on the body during the follicular phase. First, it stimulates development of the endometrium: the velvet-like interior lining of the uterus which allows the uterus to receive and support an embryo. Secondly, estrogen regulates the release of FSH from the anterior pituitary gland. At low levels, estrogen modulates the release of FSH. However, at higher levels, estrogen provides a positive feedback on the pituitary gland, inhibiting the release of FSH and stimulating the release of luteinizing hormone (“LH”).
LH is released from the anterior pituitary gland on about day 13 of the reproductive cycle. LH assists in causing ovulation: the release of an ovum (i.e., egg) from its follicle. Distal fingers or frimbrae of a fallopian tube embrace or pick up the ovum and envelope it in the distal portion of the fallopian tube, also known as the ampullae.
The ampullae is an about 2 to about 2.5 cm tubal segment of the fallopian tube having a diameter of about 1 to about 2 cm. Fertilization (union of the capacitated sperm and ovum) occurs in this portion of the fallopian tube. After fertilization, the. fertilized ovum (or embryo) slowly migrates along the fallopian tube towards the uterus. The embryo spends its first 2 to 3 days in the ampullae where the embryo (commonly referred to as a zygote at this stage of development) rapidly divides into a ball of cells.
The interluminal environment of the fallopian tube consists of a serum transudate, which is produced from the epithelial cell lining of the fallopian tube's lumen. A rich vascular supply exists along the entire length of the fallopian tube, with collateral circulation from both the uterine and ovarian arteries and veins. The serum transudate establishes an equilibrium with the epithelial cell arterioles and capillaries to supply nutrients, glucose, amino acids, and oxygen to the developing embryo in the fallopian tube. Moreover, metabolic waste, including carbon dioxide, is evacuated from serum transudate by diffusion into the capillaries. The constant supply of nutrients, glucose, amino acids, and oxygen to the developing embryo and the rapid elimination of metabolic waste, including carbon dioxide, provides an optimum environment for embryo development in the fallopian tube.
There are generally two methods of transportation of the embryo through the fallopian tube. First, the fallopian tube contracts as a muscle to move the embryo along its length towards the uterus. Second, fallopian tube epithelial cell cilia assist in moving the ovum or embryo from the ovary to the uterus. In fact, the cilia (hair like projections) create a current in the serum transudate. Both the muscle contraction and the cilia movement create a “to-and-fro” or “back-and-forth” movement within the fallopian tube. This movement of the serum transudate (i.e., fluid in the fallopian tube) and embryo creates an intraluminal circulation system which assists in distributing nutrients and oxygen to the embryo, and removing metabolic waste (including urea and carbon dioxide) away from the embryo.
After ovulation, the reproductive cycle enters the luteal phase, wherein the ovaries secrete progesterone at the cite of ovulation. The cite of ovulation on the ovary is yellow and is commonly referred to as the corpus luteum. Progesterone stops the estrogen-mediated growth of the endometrium, and maintains the endometrium so as to prepare it for the reception and support of the developing embryo.
After fertilization, the embryo begins its migration toward the uterus. At first, the rate of travel is slow and the distance of travel is short. For example, about one day after fertilization, the embryo has traveled about 1 cm through the fallopian tube toward the uterus. The rate of travel and distance traveled increases as time after fertilization elapses, and as the number of cells increases. For example, the embryo may travel another cm between day 1 and 2 post fertilization, and between day 2 and 3 post fertilization. However, the rate and distance of travel increases whereby the embryo may travel 3 cm between day 4 and 5 post fertilization (See, e.g., FIGS.
4
-
5
).
As the embryo migrates toward the uterus, it leaves the ampullae and enters the isthmus, the longest section of the fallopian tube at about 4 to 7 cm. The isthmus has both circular and longitudinal muscles which assist in the migration of the embryo toward the uterus. The embryo spends about 40-60 hours migrating through the distal portion of the isthmus, and about 15-20 hours migrating through the proximal portion of the isthmus. Thereafter, the embryo passes through the cornu and interstitial regions of the fallopian tube, taking about 3-4 hours to do so. As the embryo's cell number increases from about 2 at day one post fertilization to about 32 at five days post fertilization (see, e.g., FIG.
6
), its transit rate through the fallopian tube also increases. The increased transit rate is believed to assist in providing or making available additional nourishment to the embryo, and also to increase the rate of diffusion of waste products away from the embryo.
At about five days post fertilization (i.e., about 19 days into the reproductive cycle), the embryo enters the uterus. At this stage, the embryo is generally referred to as a blastocyst. The blastocyst may penetrate the endometrium whereby it implants and attaches to the uterine wall. At the point of implantation, the blastocyst divides into two distinct cell lines: the placental line, which will eventually develop into the placenta which assists in nourishing the fetus; and the fetal line. The placental line produces human chorionic gonadotrophin (HCG), which acts to continue the ovarian corpus luteum's production of progesterone for about 11 to 12 weeks (until the placenta has sufficient progesterone to continue the pregnancy).
Many women cannot become pregnant for a variety of reasons. For example, occlusion or dysfunction of the fallopian tubes may lead to fertility problems. One of the traditional solutions to infertility has been adoption. However, the number of healthy infants available for adoption relative to the number of people seeking to adopt has substantially decreased in recent years. As such, adoption often is not readily available to every person who wishes to adopt a child.
Alternatively, there have been attempts in the past to restore normal tubal function to occluded or dysfunctioning fallopian tubes. Surgeons have tried to repair or reconstruct damaged fallopian tubes using surgery. In addition, physicians have also tried transplanting healthy fallopian tubes from a donor. There are several drawbacks with this course of treatment. First, major surgery can be required under a general anesthetic. Second, with regard to transplant, there is the possibility of open rejection by the recipient.
Another solution to a dysfunctional fallopian tube has been to implant an artificial fallopian tube in the woman's body. An example of this is disclosed in U.S. Pat. No. 4,574,000 (Hunter). The apparatus includes a ovisac w
Campbell Michael J.
Thompson Ronald J.
Kearney Rosiland S.
Stites & Harbison
Vanderburgh John E
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