Characterization of rat pituitary luteinizing hormone charge microheterogeneity in male and female rats using chromatofocusing: effects of castration.

Chromatofocusing was used to characterize the isohormones of rat (r) LH present in extracts of pituitaries of intact and castrate, male and female rats. In each case, at least seven rLH isohormones were observed: one in the void volume of the column [isohormone I, isoelectric point (pI) greater than 9.8], five in the pH range of 9.25-8.97 (isohormones II-VI), and one which was bound to the column but could be eluted with 1.0 M NaCl (isohormone VII, pI less than 7.0). The distribution of immunoreactive rLH among the isohormones was affected by castration in both sexes but was not significantly different in intact males vs. proestrous female rats. Compared to castrates of both sexes, intact male and female rats possessed a larger percentage of immunoreactive rLH as isohormone I. All seven isohormones possessed significant LH biological activity. The bioactivity-immunoactivity (B/I) ratios of rLH isohormones from castrate female rats were significantly greater than those of intact and castrate male rats. The Bio-Index (the amount of biologically active rLH) of isohormones II-VI was markedly increased as a result of castration in both sexes. Changes in B/I ratios and amounts of immunoreactive rLH were not due to the cross-reactivity of rFSH, rTSH, and rPRL in the rLH RIA. Thus, in addition to altering the amount of rLH in the pituitary, castration also alters the pattern of rLH isohormones in the pituitary, yielding a dramatic increase in the isohormones with pI values in the range of 9.06-9.25.

Human alpha fetoprotein enhances epidermal growth factor proliferative activity upon porcine granulosa cells in monolayer culture.

Alpha fetoprotein (AFP) is present at high concentrations in fetal fluids, certain neoplasias, and regenerating liver. Its physiological function remains largely unknown. Using a primary monolayer culture system, we investigated the proliferative activity of human (h) cord blood (CB) and highly purified AFP. hAFP, purified from hCB by Cibacron blue and immunoaffinity chromatography was homogeneous on SDS-PAGE and silver stain. Porcine granulosa cells from ovarian small follicles were cultured (25,000/cm2) for 2 days in medium (Ham's F-12:DMEM, 1:1) + 5% fetal calf serum (FCS) to facilitate attachment, followed by 6 days in medium containing: FCS, hCB or h amniotic fluid (1-20%)+/- EGF (10 ng/ml); or 0.25% plasma-derived serum (PDS) containing human low density lipoprotein (LDL, 25 ug/ml), +/- AFP (0.05-5 ug), and +/- EGF and IGF-I (10 ng/ml). In this system, single growth factors do not stimulate proliferation, a characteristic also exhibited by AFP. When combined with EGF, however, AFP dose-dependently increased proliferation to levels equal to that obtained with 10% FCS (2.3-fold increase vs PDS/LDL controls). When combined with EGF+IGF-I, AFP again dose-dependently increased proliferation to levels equal to that obtained with 10% FCS+EGF (6.7-fold increase vs controls). Purified human albumin used in place of AFP was not effective. TGF-a but not PDGF could replace the proliferative activity of EGF. These results suggest that AFP at physiological levels, although not itself mitogenic, can enhance the mitogenic activity of EGF and TGF-a and may function to modulate growth factor-mediated proliferation during development and neoplasia.

Synergistic action of purified alpha-fetoprotein and growth factors on the proliferation of porcine granulosa cells in monolayer culture.

alpha-Fetoprotein (AFP) is present in high levels in fetal fluids, certain neoplasias, and regenerating liver. Although AFP's physiological role remains an enigma, we have recently demonstrated mitogenic activity for AFP. Using a primary monolayer culture system, we have further investigated the proliferative activity of purified AFP. Porcine granulosa cells from small ovarian follicles were attached for 2 days in Ham's F-12-Dulbecco's Modified Eagle's Medium (1:1) and 5% fetal calf serum, followed by 6 days of culture in medium containing 0.25% plasma-derived serum plus 25 micrograms/ml low density lipoprotein with or without growth factors and/or purified human AFP. In this system AFP alone does not stimulate proliferation. However, when combined with epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I; 10 ng/ml each), AFP (5 micrograms/ml) significantly (P less than 0.01) enhanced growth factor-mediated proliferation 4.5-fold over that of medium controls. Equivalent doses of purified human serum albumin or transferrin demonstrated no effect. The effects of AFP were dose dependent, with significant (P less than 0.05) enhancement of proliferation (2.7-fold over controls) observed with as little as 0.313 micrograms/ml AFP. Increased proliferation was noticed as early as 24 h after the addition of AFP and by 48 h AFP, EGF, and IGF-I had significantly (P less than 0.05) increased proliferation over that seen in medium controls, cells treated with EGF plus IGF-I, or cells treated with 10% fetal calf serum plus EGF, and this trend continued linearly over 5 days of culture. AFP (5 micrograms/ml) significantly increased the proliferative response observed with increasing doses of EGF, IGF-I, or EGF plus IGF-I, but did not appear to alter the dose-response curves. AFP dose-dependently (1.25-5 micrograms/ml) and significantly (P less than 0.05) increased proliferation of porcine granulosa cells in response to platelet-derived growth factor (PDGF) and EGF (25 and 10 ng/ml, respectively), but not to PDGF alone. In contrast, AFP produced no further proliferation of porcine thecal cells in response to PDGF plus EGF. Binding of EGF, IGF-I, or PDGF to purified AFP could not be demonstrated. These results demonstrate that physiological levels of AFP, although not mitogenic alone, can significantly enhance the mitogenic activity of EGF plus IGF-I/PDGF and may function to modulate growth factor-mediated cell proliferation during development and neoplasia.

Effects of epidermal growth factor on the tyrosine phosphorylation of mitogen-activated protein kinases in monolayer cultures of porcine granulosa cells.

We have examined porcine granulosa cells (pGCs) for the presence of immunodetectable mitogen-activated protein (MAP) kinases (extracellular signal-regulated kinases, ERK) and have further studied the effects of epidermal growth factor (EGF) on the activation of these kinases. Cell lysates prepared from untreated monolayer cultures of pGCs were subjected to Western immunoblotting analysis using monoclonal antibodies to ERK1, ERK2 and pan-specific ERK. MAP kinases were detected having mol wts of 87K (ERK87), 54K (ERK54), 44K (ERK1), and 42K (ERK2). Treatment of pGCs with increasing concentrations (1-10 ng/ml) of EGF for 10 min resulted in electrophoretic mobility shifts of ERK1 and ERK2 suggesting hyperphosphorylation. Immunoprecipitation with an antiphosphotyrosine antibody (PY20), followed by Western analysis using pan-ERK, revealed a marked concentration-dependent increase in tyrosine phosphorylation of ERK2 in response to EGF treatment. The mobility shift and tyrosine phosphorylation of ERK2 was observed as early as 1 min after treatment with 10 ng/ml EGF. In-gel myelin basic protein (MBP) kinase assays revealed significant MBP kinase activity associated with ERK1 and ERK2 in total cell lysates and ERK2 in PY20 immunoprecipitates. Although ERK1 displayed a moderate mobility shift in response to EGF, tyrosine phosphorylation of this MAP kinase was not appreciably increased by EGF. Furthermore, PY20 immunoprecipitates demonstrated minimal MBP kinase associated with ERK1 in response to EGF treatment. Electrophoretic migration, tyrosine phosphorylation, and MBP kinase activity of the ERK54 and ERK87 was not effected regardless of EGF concentration or duration of treatment. These data demonstrate for the first time that pGCs contain immunodetectable MAP kinases. EGF, in a concentration- and time-dependent manner, increases tyrosine phosphorylation and MBP kinase activity (i.e. activation) of ERK2, and to a lesser degree ERK1, suggesting that the activation of MAP kinase may mediate the mitogenic action of EGF in pGCs.

Purified human alpha fetoprotein inhibits growth factor-stimulated estradiol production by porcine granulosa cells in monolayer culture.

Purified alpha fetoprotein (AFP) synergizes with transforming growth factor alpha (TGF alpha) and insulin-like growth factor I (IGF-I) to enhance proliferation of porcine granulosa cells (pGC) in primary culture, suggesting a role for AFP in the modulation of growth factor-mediated cell growth. TGF alpha stimulates basal estrogen production by pGC and is in fact more potent than FSH in these cells. In this study, we investigated the effects of AFP on growth factor-stimulated estradiol (E2) production by pGC. Basal production of E2 was not altered by the addition of AFP. AFP dose-dependently inhibited TGF alpha-stimulated E2 production with statistically significant inhibition observed with 2.5 micrograms/ml. We have previously shown that the mitogenic effects of AFP are maximized with TGF alpha+IGF-I. E2 production was even more sensitive to AFP inhibition when the two growth factors were combined. Human serum albumin (HSA; 10 micrograms/ml) was without effect. AFP did not interfere with the E2 RIA, affect the uptake of or display specific in vitro binding of the androgen substrate. Furthermore, human AFP and HSA did not exhibit specific in vitro binding of E2, in contrast to purified rat AFP (positive control). These data indicate that physiological concentrations of purified AFP significantly and dose-dependently inhibit growth factor-stimulated E2 production by pGC in culture. Since AFP is known to increase TGF alpha+IGF-I mediated cell growth, these data suggest that AFP may be inhibiting the differentiated function (steroidogenesis) of pGC while enhancing the proliferation of these cells.

Oestrogenic regulation of testicular androgen production during development in the rat.

The influence of age on the sensitivity of the testis to oestrogens was investigated. Intact male rats at 10, 25, 40 and 53 days of age were injected s.c. with vehicle, 5 or 50 micrograms oestradiol or diethylstilboestrol (DES)/100 g body wt twice daily for 2 days; the animals were killed 12 h after the last injection. Subsequently, the concentrations of testicular androgens and serum LH, prolactin, testosterone and androstanediol (5 alpha-androstane-3 alpha, 17 beta-diol) were measured. Testicular androgen production was determined in vitro in the presence or absence of human chorionic gonadotrophin (hCG) or dibutyryl cyclic AMP (dbcAMP). Androgens in the serum and testes displayed an age-related alternating pattern with androstanediol being the major androgen produced at 27 days of age. As a result of oestrogen treatment, serum LH concentrations were decreased while serum prolactin was increased. Serum testosterone was decreased by 36-55% in the 12-day-old group and further reduced by 95% of control values by day 55; serum androstanediol was less sensitive to oestrogen suppression. Testicular concentrations of both testosterone and androstanediol exhibited a marked reduction in 12-day-old animals as a result of oestrogen administration. These values were reduced by 85-95% at day 27 and remained suppressed even at 55 days. Basal production of testosterone was unaffected by oestrogen treatment in 12- and 27-day-old animals but was markedly decreased by day 42. Significant suppression of basal production of androstanediol was observed as early as day 12.(ABSTRACT TRUNCATED AT 250 WORDS)

Minimal quantities of FSH beta subunit are released by rat anterior pituitary cells in primary culture.

FSH beta in the medium and extracts of cultured rat anterior pituitary cells was quantitated with a heterologous radioimmunoassay utilizing anti-rFSH beta and hFSH beta as the standard and tracer. After 4 days in culture, extracts were prepared from washed cells, cells incubated for 6 h or 24 h in fresh medium or cells incubated for 6 h in the presence of 10(-7) M GnRH. FSH beta/rFSH molar ratios were approximately 0.05, 0.04, 0.21 and 0.35, respectively. The elevation in FSH beta/rFSH molar ratios in 24 h basal and GnRH-treated cultures was due in part to an increase in intracellular FSH beta. Both unstimulated and GnRH-treated cultures contained non-detectable quantities of FSH beta in the medium (less than 0.063 ng/100 000 cells; FSH beta/rFSH molar ratio less than 0.024). Thus, it appears that cultured rat anterior pituitary cells contain a small amount of uncombined FSH beta but that minimal quantities are released. Furthermore, GnRH may increase intracellular quantities of FSH beta but does not induce its release.

Purified human alpha-fetoprotein inhibits follicle-stimulating hormone-stimulated estradiol production by porcine granulosa cells in culture.

We have investigated the effects of purified alpha-fetoprotein (AFP) on follicle-stimulating hormone (FSH)-stimulated estradiol production by porcine granulosa cells in monolayer culture. Granulosa cells isolated from small follicles of prepubertal pigs were cultured for 2 days in 5% fetal bovine serum for attachment and incubated for 3 days in medium containing androstenedione and various treatments. The media were then collected and assayed for estradiol by radioimmunoassay. Human AFP significantly (P < 0.05) and dose-dependently inhibited FSH-stimulated estradiol production with 313 ng/ml AFP returning FSH-stimulated estradiol to basal levels; human serum albumin was without effect. AFP purified from either term cord blood or midtrimester amniotic fluid dose-dependently inhibited estradiol production stimulated by the combination of FSH and insulin-like growth factor-I. Furthermore, 125 ng/ml AFP inhibited estradiol production stimulated by cholera toxin, forskolin and cAMP. In contrast, extracellular accumulation of cAMP and progesterone production was not inhibited by AFP. These data indicate that physiological concentrations of purified AFP significantly and dose-dependently inhibit FSH-stimulated estradiol production by porcine granulosa cells in culture. Since AFP is known to augment growth factor-mediated cell growth, these data suggest that AFP inhibits differentiated functions (such as aromatase) while enhancing the proliferation of porcine granulosa cells.

Quantitation of LH subunits released by rat anterior pituitary cells in primary culture.

Immunoreactive rLH, rLH alpha, rLH beta and rFSH in the cell extracts and medium of rat anterior pituitary cell cultures were measured after gel filtration on Sephadex G-100 Superfine. Cell extracts contained uncombined rLH alpha and rLH beta present as approximately 40% and 4%, respectively, of native rLH on a molar basis. Unstimulated cultures appeared to release a large excess of rLH alpha (approximately 2560% of rLH on a molar basis) as well as a minimum of uncombined rLH beta. Stimulation of cultures with physiological (LHRH) or non-physiological agents (A23187, elevated K+) increased the absolute but not the relative quantities of uncombined subunits released relative to those present intracellularly. Thus, rat anterior pituitary cell cultures appear to produce and release an excess of free alpha subunit as well as a minimum of uncombined rLH beta. However, one cannot be certain whether the uncombined rLH beta represents a pool of 'free' rLH beta or simply results from the dissociation of rLH.

Correlation between follicle-stimulating hormone, luteinizing hormone, prolactin, and testosterone with sperm cell concentration and motility.

Follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), and testosterone were measured by radioimmunoassay in blood and seminal plasma of normo-spermic and oligospermic men. These parameters were correlated with sperm cell concentration as well as sperm motility. Average motility in the oligospermic group was significantly decreased as compared with the normospermic group (P less than .001). A significant reciprocal correlation was demonstrated between blood LH concentrations and sperm cell concentrations (P less than .05) as well as sperm motility (P less than .02). In contrast, a significant positive correlation was demonstrated between seminal LH concentrations and sperm cell count and motility (P less than .001). Seminal FSH and testosterone concentrations were positively correlated with sperm output but not sperm motility (P less than .05). The increased concentrations of LH in circulation accompanying idiopathic oligospermia suggests that LH secretion may be linked to the factors regulating spermatogenesis. The significant correlation between seminal testosterone and sperm concentration demonstrated in this study offers further support to this hypothesis. The significance of the correlation between the levels of LH and FSH in seminal plasma and sperm cell concentration and sperm motility is unknown.

Correlation of human sperm motility characteristics with an in vitro cervical mucus penetration test.

Semen analysis was performed on 226 ejaculates by an integrated microcomputerized system employing the multiple-exposure photography (MEP) method. Mucus penetration tests were performed in vitro using commercial preparations of bovine cervical mucus. A highly significant (P less than 0.001) correlation between mucus penetration distance and sperm count (r = 0.582), motility (r = 0.357), velocity (r = 0.569), motile density (r = 0.582), motility index (r = 0.467), and morphology (r = 0.383) was observed. Increased percentages of immature germ cells (r = -0.318) and bent-tailed sperm (r = -0.221) were the most strongly correlated with mucus penetration. Approximately 10% to 15% of patients with otherwise normal semen parameters displayed poor penetration of mucus. Conversely, 5% to 40% of patients with abnormal semen parameters displayed excellent penetration of the mucus. Motile density and velocity demonstrated the strongest relationship with the outcome of the mucus penetration test. These results suggest that a significant subpopulation of patients can be identified as having inadequate (or adequate) penetration of mucus with otherwise normal (or abnormal) motility characteristics.

Semen analysis data from fresh and cryopreserved donor ejaculates: comparison of cryoprotectants and pregnancy rates.

Patients (155) were selected at random for fresh or cryopreserved semen and inseminated on the predicted day of ovulation. Semen analysis was performed using a microcomputerized multiple-exposure photography system. Frozen semen was used with either glycerol or TEST-yolk (TEST-buffered 20% egg yolk with 10% glycerol) as the cryoprotectant. Cryopreservation resulted in significant decreases in all semen parameters measured. Of these, velocity appeared to be the least effected. TEST-yolk provided significantly more protection against a reduction in velocity compared with glycerol. A total of 18, 17, and 27 patients conceived using fresh, glycerol, or TEST-yolk-preserved semen, respectively. For these same groups, a cumulative pregnancy rate of 52.9%, 27.1%, and 68.5%, respectively, was observed (not significant). The total number of motile sperm per insemination used for fresh artificial inseminations resulting in conception (132.4 X 10(6] was significantly greater than the number used for successful glycerol- and TEST-yolk-preserved semen (approximately 24 X 10(6]. These results demonstrate that although the number of motile sperm of cryopreserved ejaculates are dramatically reduced compared with the fresh counterparts, if a minimum criteria for ejaculate quality is established, the use of cryopreserved semen can offer a viable, effective, and relatively safe alternative to artificial insemination by donor with fresh semen.

Variation in the biologic and biochemical characteristics of human menopausal gonadotropin.

Lot differences in the biopotency of human menopausal gonadotropin (hMG) were evaluated and the potential biochemical basis was investigated. The in vivo biopotency of hMG was assessed by a unique bioassay that evaluates the number of ova shed in the cyclic hamster in response to hMG administration. Significant variation in hMG lots was observed using this assay. When subjected to chromatofocusing, hMG displayed five immunoreactive follicle-stimulating hormone (FSH) isohormones and nine luteinizing hormone (LH) isohormones. The relative distribution of FSH, but not LH isohormones, was slightly but significantly different between the lots tested. These data indicate that significant differences exist in the ability of commercially available hMG to stimulate follicular development and ovulation. The biochemical basis for these differences in in vivo biopotency remains to be elucidated.

Heterogeneity of gonadotropins and levels of uncombined luteinizing hormone subunits in pituitaries of cryptorchid rams.

Pituitaries were collected from intact rams and rams that had been rendered bilaterally cryptorchid by surgery to examine the effects of cryptorchidism on gonadotropin heterogeneity, levels of uncombined luteinizing hormone (LH) subunits, and the apparent molecular sizes of LH and follicle-stimulating hormone (FSH). Cryptorchid rams had higher pituitary contents of LH and FSH as well as reduced testicular weights. The levels of uncombined LH subunits, their apparent molecular weights, and the apparent molecular weights of intrapituitary LH were similar in control and cryptorchid rams. However, the apparent molecular weight of intrapituitary FSH was slightly larger in cryptorchid rams. Cryptorchidism altered the pattern of gonadotropin heterogeneity by shifting the distribution of LH isoforms towards basic components and shifting the distribution of FSH isoforms towards acidic components. Thus, it appears that the altered gonadal feedback mechanisms resulting from cryptorchidism modify the pattern of both LH and FSH heterogeneity by shifting the distribution of isoforms in opposite directions.

Epidermal growth factor activates extracellular signal-regulated protein kinases (ERK) in freshly isolated porcine granulosa cells.

We investigated the ability of EGF to stimulate the phosphorylation (i.e. activation) of extracellular signal-regulated kinases (ERKs) in freshly isolated porcine granulosa cells (pGC) held in suspension. pGCs were isolated from the ovaries of prepubertal pigs at slaughter, and equilibrated for 24 h at 37 degrees C in 12 x 75 mm culture tubes. The cells were then treated with 0-10 ng/ml EGF for 1-240 min. Treatments were terminated, and the total cell lysates were subjected to SDS-PAGE and Western analysis. The Westerns were blotted with anti-panERK and with anti-phosphoERK, antibodies that recognize all forms of ERKs and the phosphorylated (i.e. activated) forms of ERKs, respectively. Western blot analysis with the panERK antibody revealed a gel shift of ERKs, suggesting hyperphosphorylation after treatment with as little as 0.1 ng/ml of EGF. Phosphorylation of the ERKs was confirmed by using the phosphoERK antibody, which indicated increased phosphorylation of ERKs above control with 0.1 ng/ml EGF and maximal phosphorylation of ERK with 5-10 ng/ml EGF. Activation of ERK by EGF, as measured by both gel shift analysis and active ERK blotting, in the freshly isolated pGC was rapid, increasing above controls after 1 min of treatment, maintaining high levels through 40 min, and declining from 60 to 240 min. These data indicate that EGF stimulates active ERK in a time- and concentration-dependent manner in freshly isolated pGCs and that this experimental approach represents an effective manner with which to evaluate the role of EGF and the ERK signal transduction pathway in freshly harvested pGC.

Human mammary tumor cell proliferation: primary role of platelet-derived growth factor and possible synergism with human alpha-fetoprotein.

Human mammary medullary carcinoma cells (passages 16 to 21) were cultured for 2 days to allow for attachment, followed by 6 days of culture in either fetal calf serum, human cord blood, human amniotic fluid, or growth factors in the presence or absence of purified human alpha-fetoprotein (AFP). When growth factors were tested alone, only platelet-derived growth factor produced a significant increase in cell proliferation. Although up to 40% amniotic fluid had no effect on cell proliferation, human cord blood was two-fold more potent than fetal calf serum at similar concentrations. The addition of 10 ng/ml of platelet-derived growth factor increased the proliferative activity of human cord blood 1.5- to 2.5-fold. Ablation of endogenous AFP by affinity chromatography reduced the proliferative activity of cord blood by 75%. Similarly, the mitogenic activity of cord blood plus platelet-derived growth factor was reduced by 56% when AFP was removed. Purified AFP dose-dependently enhanced the proliferative activity of platelet-derived growth factor. This synergistic effect was specific for platelet-derived growth factor. We conclude that platelet-derived growth factor is a major growth factor controlling the proliferation of these tumor cells and that AFP may enhance growth factor proliferative activity and human mammary tumor growth.

Mechanisms of hormone and growth factor action in the bovine corpus luteum.

The binding of hormones and growth factors to their cell surface receptors leads to an orderly cascade of events leading to activation of cytoplasmic effector molecules. The mechanism of action of luteinizing hormone involves the stimulation of multiple signal transduction effector systems including adenylyl cyclase and inositol phospholipid-specific phospholipase C (PLC). This results in the formation of second messengers that activate cAMP-dependent, Ca(2+)-dependent and lipid-dependent protein kinases. Prostaglandin F(2alpha) activates PLC which increases intracellular calcium and activates protein kinase C. This results in the activation of a series of protein kinases in the mitogen-activated protein (MAP) kinase cascade, leading to the activation of nuclear transcription factors c-fos and c-jun. Hormone responsive effector systems, therefore, operate by activating families of protein kinases which regulate cell metabolism, secretion, and gene transcription. Growth factors activate specific receptor protein tyrosine kinases which recruit additional signaling molecules (phospholipase Cgamma, phosphatidylinositol 3-kinase, Shc, Grb2, etc.) initiating a cascade of events mediated via MAP kinases. The signaling pathways activated by hormones interact or cross talk with the signaling pathways activated by growth factors. The diversity of cellular signaling mechanisms elicited by hormones and the potential for interactions with signals generated by growth factor receptor tyrosine kinases, may allow fine tuning of cellular responses during the life span of the corpus luteum.

Effects of aging on biologically active pituitary LH in rats.

The effects of aging in the male rat on serum testosterone and LH and on the amounts of immunoreactive and biologically active pituitary LH were studied. Animals were killed at three, six, 12 and 24 months of age and serum and pituitary extracts prepared. Serum testosterone was significantly reduced by six months of age and remained at this low level throughout the study. The serum testosterone circadian rhythm was severely blunted in old animals. Serum LH was not effected by aging. Pituitary immunoreactive LH content was significantly decreased by 24 months of age, whereas the biological to immunological (B/I) ratio was not altered. However, the absolute amount of biologically active pituitary LH declined steadily with age from six months. These age-related effects were not caused by a gross redistribution of pituitary LH charge isohormones. These results suggest that the hypostimulated testis in the aging male rat may be related to a reduced amount of biologically active LH available for secretion.

Motility characteristics of human sperm, nonfrozen and cryopreserved.

Ejaculates (1651) obtained by masturbation from 88 donors were evaluated for count, motility, and kinetics. After the initial evaluation the ejaculates were frozen in liquid nitrogen, thawed 24 hr later, and assessed for postthaw motility and kinetics. The ejaculates were then divided into seventeen groups according to sperm count and evaluated to determine if direct relationships exist between prefreeze and thawed semen characteristics. The average sperm count was 151 X 10(6) sperm/ml. The freezing process resulted in a reduction of motility from a mean of 85% to a mean of 52%. Postthaw motility increased with sperm count up to 120 X 10(6) sperm/ml where there appeared to be no further effect. Linear regression analysis demonstrated a high correlation between prefreeze motility and postthaw motility (r = 0.947). Cryopreservtion of human spermatozoa results in a significant reduction of motility. A direct relationship exists between prefreeze and postthaw motility and prefreeze motility may be an important factor in evaluating the potential of an ejactulate to withstand cryopreservation.