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Recent studies have shown that zygote morphology could be used for the assessment of human embryo quality. Pronuclear (PN) morphology is based on certain distinct features seen in zygotes 16-18 h after fertilization. In the present study PN stage morphology was assessed and combined with a single embryo transfer in order to investigate whether currently used zygote classifications are able to predict embryo quality and implantation rates.

In this prospective study we investigated whether the maturation and fertilization of immature oocytes can be improved by administration of recombinant follicle stimulating hormone (rFSH) starting in the late luteal phase in two groups of women: group 1 (n = 6) women with regular menstrual cycles; and group 2 (n = 6) women with irregular cycles and polycystic ovaries (PCO) on ultrasound examination. Low-dose (37.5 IU) rFSH was commenced 11 days after LH surge during a spontaneous menstrual cycle and on the ninth day of progesterone administration in an irregular cycle. Recombinant FSH was continued until the leading follicle was approximately 10 mm in diameter. The oocytes were retrieved after withdrawing rFSH for 2-5 days. In total, 136 oocytes were recovered (group 1, 67 oocytes; group 2, 69 oocytes). Nine of the oocytes from PCO women were atretic at retrieval. Oocytes complete with cumulus cells were cultured for 44 h in complex tissue culture medium supplemented with gonadotrophins and fetal calf serum. After maturation, the cumulus cells were removed and metaphase II oocytes were injected with spermatozoa. Respectively, the oocyte maturation and fertilization rates were 64 and 72% in group 1, and 78 and 57% in group 2 (not significant). After fertilization, the zygotes (group 1, n = 22; group 2, n = 11) and cleavage stage embryos (group 1, n = 9; group 2, n = 15) were frozen in propanediol. All women except one (11/12) had approximately five zygotes or cleaved embryos frozen. The viability of in-vitro matured frozen-thawed embryos was generally poorer than that (81%) seen after conventional intracytoplasmic sperm injection, with 61% survival in group 1 and 23% in group 2. Fifteen embryo transfers resulted in one miscarriage at 6 weeks gestation. The late luteal start of low-dose rFSH yielded a good number of immature oocytes in women with both regular and irregular cycles. Two out of three of these oocytes matured and fertilized. However, cryosurvival of the zygotes and cleaved embryos was unsatisfactory and thus cryopreservation of in-vitro matured embryos may not be an optimal procedure.

Using testicular spermatozoa from either open biopsy (29 cycles) or biopty gun needle biopsy (49 cycles), a total of 81 intracytoplasmic sperm injection (ICSI) cycles among 57 couples were carried out from January, 1994 to September, 1997. In six cycles, no spermatozoa were obtained, and in three cycles spermatozoa from both needle and open biopsies were used. The fertilization (37% after open and 41% after needle biopsy) and pregnancy rates (29% per embryo transfer compared with 16% per embryo transfer) were similar after both open and needle biopsies. Five pregnancies were achieved among the 14 couples with non-obstructive azoospermia of the male partner, four of these after needle biopsy. It was possible to use cryopreserved testicular spermatozoa after both needle and open biopsies, and one pregnancy started after using cryopreserved testicular spermatozoa in both groups. Histological needle biopsy was carried out in 62 cases, and they were all diagnostic, giving 15-20 cross-sections of seminiferous tubuli per biopsy. Testicular needle biopsy using a 14 gauge biopsy needle gave a sufficient amount of tissue and spermatozoa for ICSI, cryopreservation and histology, even in non-obstructive azoospermia. This technique is simpler and cheaper than open biopsy and, hence, it can be regarded as the optimal method for the retrieval of testicular spermatozoa.

Recent studies have indicated that activin A/erythroid differentiation factor is a physiologic hematopoietic growth and differentiation factor mainly for cells of the erythroid lineage. We studied the expression of the two type II activin receptor mRNAs during the differentiation of K562 erythroleukemic cells, which are known to be induced toward the erythroid lineage in response to activin or toward the megakaryoblastic lineage by phorbol myristate acetate (PMA). The cDNA of the human activin receptor type IIB (hActR-IIB) was cloned and sequenced from two RNA sources, the K562 cells and the human fetal brain, which is, of the tissues screened by Northern blot analysis, the most abundant source of ActR-IIB RNA. The cDNA encodes a predicted 512 amino acid protein containing an extracellular ligand binding domain, a hydrophobic transmembrane domain, and an intracellular serine/threonine kinase domain. The amino acid sequence is 99.2% and 98.4% homologous in the coding region to the previously described mouse and rat ActR-IIB2s, respectively, and 69% identical to the other human activin serine/threonine kinase receptor, hActR-II. The alternative splicing events in the juxtamembrane region previously reported for the respective mouse receptor were not observed during the processing of K562 cell and human fetal brain RNA. Northern analysis showed that the 10- and 2.5-kb transcripts of hActR-IIB are more abundantly expressed than the 6.0- and 3.0-kb transcripts of hActR-II in K562 cells. No changes in the steady-state levels of hActR-II and IIB mRNAs were detected upon differentiation of K562 cells by activin A or by PMA. Similarly, the receptor mRNA levels remained constant in HL-60 cells induced to either monocyte/macrophage or granulocyte-like cells by PMA or dimethyl sulfoxide, respectively. Thus, the mRNA expression levels of both receptors apparently do not correlate with the differentiation status of these cells.