An L314Q mutation in Map3k1 gene results in failure of eyelid fusion in the N-ethyl-N-nitrosourea-induced mutant line.

In this study, we describe an N-ethyl-N-nitrosourea-induced mouse model with a corneal opacity phenotype that was associated with "eye open at birth" (EOB). Histological and immunohistochemistry staining analysis showed abnormal differentiation of the corneal epithelial cells in the mutant mice. The EOB phenotype was dominantly inherited on a C57BL/6 (B6) background. This allele carries a T941A substitution in exon 4 that leads to an L314Q amino acid change in the open reading frame of MAP3K1 (MEEK1). We named this novel Map3k1 allele Map3k1L314Q. Phalloidin staining of F-actin was reduced in the mutant epithelial leading edge cells, which is indicative of abnormality in epithelial cell migration. Interestingly enough, not only p-c-Jun and p-JNK but also c-Jun levels were decreased in the mutant epithelial leading edge cells. This study identifies a novel mouse Map3k1 allele causing EOB phenotype and the EOB phenotype in Map3k1L314Q mouse may be associated with the reduced level of p-JNK and c-Jun.

Pseudoesotropia in Chinese Children: A Triphasic Development of the Interepicanthal Folds Distance-to-Interpupillary Distance Ratio and Its Changing Perception.

PURPOSE: To delineate the development of the interepicanthal fold distance (IEFD) to interpupillary distance (IPD) in Chinese children, and to quantify how their ratio (EFDPD ratio) affects parent's judgment on whether a child's two eyes appear misaligned. METHODS: The values of IPD and IEFD were measured in 750 children, aged between 3 and 17 years. The developmental trend of EFDPD ratio was established. Two hundred parents were shown a series of pictures of children with varying EFDPD ratios and asked to judge whether the child in each picture demonstrated misaligned eyes. Based on the parent's responses, psychometric functional associations with EFDPD ratios were established. RESULTS: The EFDPD ratios were significantly higher (0.63 ± 0.027) and showed little change among children from 3 to 6 years of age (p = 0.704). During the age of seven to 12 years, however, the EFDPD ratio significantly decreased (p < 0.001) before stabilizing at 0.59 ± 0.023 by the ages of 13 to 17 years (p = 0.376). Children with EFDPD ratios > 0.65 were more likely to be perceived as strabismic by the parents, while children with an EFDPD ratio < 0.55 were rarely perceived as so. As many as 30% of the children aged between 3 and 6 years demonstrated EFDPD ratios > 0.65, and this number reduced to 5% by the age of 12 years. CONCLUSIONS: The development of the EFDPD ratio in Chinese children shows a triphasic pattern, with a large value before the age of 6 years, a quick drop between 7 and 12 years, and little change after 13 years of age. As the EFDPD ratio declines, fewer children appear as strabismic. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Genetic background-dependent role of Egr1 for eyelid development.

EGR1 is an early growth response zinc finger transcription factor with broad actions, including in differentiation, mitogenesis, tumor suppression, and neuronal plasticity. Here we demonstrate that Egr1-/- mice on the C57BL/6 background have normal eyelid development, but back-crossing to BALB/c background for four or five generations resulted in defective eyelid development by day E15.5, at which time EGR1 was expressed in eyelids of WT mice. Defective eyelid formation correlated with profound ocular anomalies evident by postnatal days 1-4, including severe cryptophthalmos, microphthalmia or anophthalmia, retinal dysplasia, keratitis, corneal neovascularization, cataracts, and calcification. The BALB/c albino phenotype-associated Tyrc tyrosinase mutation appeared to contribute to the phenotype, because crossing the independent Tyrc-2J allele to Egr1-/- C57BL/6 mice also produced ocular abnormalities, albeit less severe than those in Egr1-/- BALB/c mice. Thus EGR1, in a genetic background-dependent manner, plays a critical role in mammalian eyelid development and closure, with subsequent impact on ocular integrity.

Defective eyelid leading edge cell migration in C57BL/6-corneal opacity mice with an "eye open at birth" phenotype.

Development of the eyelid requires coordination of the cellular processes involved in proliferation, cell size alteration, migration, and cell death. C57BL/6J-corneal opacity (B6-Co) mice are mutant mice generated by the administration of N-ethyl-N-nitrosourea (100 mg/kg). They exhibit the eyelids open at birth phenotype, abnormal round cell shape from tightened F-actin bundles in leading edge keratinocytes at E16.5, and gradual corneal opacity with neovessels. The tip of the leading edge in B6-Co mice did not move forward, and demonstrated a sharp peak shape without obvious directionality. Analysis of the biological characteristics of B6-Co mice demonstrated that abnormal migration of keratinocytes could affect eyelid development, but proliferation and apoptosis in B6-Co mice had no effect. Mutant gene mapping and sequence analysis demonstrated that in B6-Co mice, adenosine was inserted into the untranslated regions, between 3030 and 3031, in the mRNA 3'-terminal of Fgf10. In addition, guanine 7112 was substituted by adenine in the Mtap1B mRNA, and an A2333T mutation was identified in Mtap1B. Quantitative real-time polymerase chain reaction analysis showed that expression of the Hbegf gene was significantly down-regulated in the eyelids of B6- Co mice at E16.5, compared to B6 mice. However, the expression of Rock1, Map3k1, and Jnk1 genes did not show any significant changes. Abnormal keratinocyte migration and down-regulated expression of the Hbegf gene might be associated with impaired eyelid development in B6-Co mice.

Genome-Wide Association Identifies SLC2A9 and NLN Gene Regions as Associated with Entropion in Domestic Sheep.

Entropion is an inward rolling of the eyelid allowing contact between the eyelashes and cornea that may lead to blindness if not corrected. Although many mammalian species, including humans and dogs, are afflicted by congenital entropion, no specific genes or gene regions related to development of entropion have been reported in any mammalian species to date. Entropion in domestic sheep is known to have a genetic component therefore, we used domestic sheep as a model system to identify genomic regions containing genes associated with entropion. A genome-wide association was conducted with congenital entropion in 998 Columbia, Polypay, and Rambouillet sheep genotyped with 50,000 SNP markers. Prevalence of entropion was 6.01%, with all breeds represented. Logistic regression was performed in PLINK with additive allelic, recessive, dominant, and genotypic inheritance models. Two genome-wide significant (empirical P<0.05) SNP were identified, specifically markers in SLC2A9 (empirical P = 0.007; genotypic model) and near NLN (empirical P = 0.026; dominance model). Six additional genome-wide suggestive SNP (nominal P<1x10(-5)) were identified including markers in or near PIK3CB (P = 2.22x10(-6); additive model), KCNB1 (P = 2.93x10(-6); dominance model), ZC3H12C (P = 3.25x10(-6); genotypic model), JPH1 (P = 4.68x20(-6); genotypic model), and MYO3B (P = 5.74x10(-6); recessive model). This is the first report of specific gene regions associated with congenital entropion in any mammalian species, to our knowledge. Further, none of these genes have previously been associated with any eyelid traits. These results represent the first genome-wide analysis of gene regions associated with entropion and provide target regions for the development of sheep genetic markers for marker-assisted selection.

Evaluation of some facial anthropometric parameters in an Iranian population: infancy through adolescence.

OBJECTIVES: By finding the mean value of anthropometric parameters in normal samples of a population, it is possible to create a template for facial analysis. The aim of our study was to measure the anthropometric parameters in 0- to 12-year-old girls of Fars ethnic origin in the Northeast of Iran. STUDY DESIGN: Six hundred sixty-two newborn to 12-year-old girls of Fars ethnic origin participated in the study. A digital camera was used to take frontal full-face photographs of each child. Thirteen measurements were taken with the Smile Analyzer software: al-al, ch-ch, en-en, ex-ex, ft'-ft', go'-go', t-t, zy'-zy', n'-gn', n'-sn, t-g', t-gn', t-sn. Data were analyzed using the SPSS software at the significance level of 0.05. RESULTS: In almost all parameters, we found significant growth acceleration between 2 and 4 years as well as 5 and 6 years of age. Another growth spurt was seen between 9 and 11 years, although it was less noticeable. Comparing the linear regression equations suggests that different craniofacial dimensions do not grow similarly. CONCLUSIONS: By age, craniofacial dimensions change at different rates. Different craniofacial dimensions do not grow at consistent rates. Some parts grow slower compared with others. The intercanthal width has the slowest growth. Facial height shows the fastest growth.

The expression of Pax6 variants is subject to posttranscriptional regulation in the developing mouse eyelid.

Pax6 is a pivotal transcription factor that plays a role during early eye morphogenesis, but its expression and function in eyelid development remain unknown. In this study, the expression patterns of Pax6 mRNA and protein were examined in the developing mouse eyelid at embryonic days 14.5, 15.5, and 16.5. The function of Pax6 in eyelid development was determined by comparing it to that in the eyes-open-at-birth mutant mouse. In the normally developing eyelid, Pax6 and Pax6(5a) mRNA levels were low at E14.5, increased at E15.5, and then declined at E16.5, accompanied by a change in the Pax6/Pax6(5a) ratio. Pax6 protein was mainly located in the mesenchyme and conjunctiva. It was expressed at low levels in the epidermis at E14.5, severely reduced at E15.5, but re-expressed in the keratinocyte cells of the periderm at E16.5. In contrast, Pax6 and the Pax6/Pax6(5a) ratio were considerably higher with strong nuclear expression in the mutant at E15.5. Next, we examined the relationship of Pax6 to epidermal cell proliferation, migration, and the associated signalling pathways. The Pax6 protein in the developing eyelid was negatively correlated with epidermal cell proliferation but not migration, and it is in contrast to the activation of the EGFR-ERK pathway. Our in vivo data suggest that Pax6 expression and the Pax6/Pax6(5a) ratio are at relatively low levels in the eyelid, and acting as a transcription factor, Pax6 is required for the initiation of eyelid formation and for differential development of the keratinised cells in the closed eyelid. The Pax6 protein is likely to be controlled by the EGFR-ERK pathways. An abnormal increase in Pax6 expression and the Pax6/Pax6(5a) ratio due to alteration of the pathway activity could suppress epidermal cell proliferation leading to the eyes-open-at-birth defect. This study offers insight into the function of the Pax6 protein in eyelid development.

FGF-regulated BMP signaling is required for eyelid closure and to specify conjunctival epithelial cell fate.

There are conflicting reports about whether BMP signaling is required for eyelid closure during fetal development. This question was addressed using mice deficient in BMP or TGFbeta signaling in prospective eyelid and conjunctival epithelial cells. Genes encoding two type I BMP receptors, the type II TGFbeta receptor, two BMP- or two TGFbeta-activated R-Smads or the co-Smad Smad4 were deleted from the ocular surface ectoderm using Cre recombinase. Only mice with deletion of components of the BMP pathway had an 'eyelid open at birth' phenotype. Mice lacking Fgf10 or Fgfr2 also have open eyelids at birth. To better understand the pathways that regulate BMP expression and function during eyelid development, we localized BMPs and BMP signaling intermediates in Fgfr2 and Smad4 conditional knockout (CKO) mice. We found that Fgfr2 was required for the expression of Bmp4, the normal distribution of Shh signaling and for preserving the differentiation of the conjunctival epithelium. FGF signaling also promoted the expression of the Wnt antagonist Sfrp1 and suppressed Wnt signaling in the prospective eyelid epithelial cells, independently of BMP function. Transcripts encoding Foxc1 and Foxc2, which were previously shown to be necessary for eyelid closure, were not detectable in Smad4(CKO) animals. c-Jun, another key regulator of eyelid closure, was present and phosphorylated in eyelid periderm cells at the time of fusion, but failed to translocate to the nucleus in the absence of BMP function. Smad4(CKO) mice also showed premature differentiation of the conjunctival epithelium, conjunctival hyperplasia and the acquisition of epidermal characteristics, including formation of an ectopic row of hair follicles in place of the Meibomian glands. A second row of eyelashes is a feature of human lymphedema-distichiasis syndrome, which is associated with mutations in FOXC2.

Blefarorrafia eversora temporária na correção do entrópio de desenvolvimento em cães da raça Shar Pei / Temporary evertor blepharorrhaphy in the correction of developmental entropion in Shar Pei dogs

O entrópio de desenvolvimento é uma alteração palpebral de ocorrência freqüente em cães da raça Shar Pei, determinando lesões que podem ocasionar perda da função visual. A doença tem um caráter genético na raça, mas há uma importante participação de fatores morfológicos predisponentes, que incluem excesso de pele e rugas na região da cabeça e má justaposição entre as pálpebras e o bulbo ocular. Os sinais iniciais de fotofobia, epífora, inversão da pálpebra superior e conjuntivite são agravados pelo componente espástico resultante do blefarospasmo, determinando alterações mais sérias que incluem ulceração corneana e phthisis bulbi. O recrudescimento dos sinais clínicos é observado com o crescimento do animal naqueles casos em que não são realizados procedimentos preventivos. O objetivo do presente estudo foi avaliar os aspectos clínicos do entrópio em filhotes da raça Shar Pei e desenvolver uma nova técnica de blefarorrafia eversora temporária, capaz de impedir a progressão do quadro clínico e prevenir lesões bulbares, evitando-se a necessidade de futuras cirurgias corretivas. Utilizaram-se 50 animais com idades entre 18 e 128 dias, que apresentavam graus variáveis de inversão palpebral e lesões oculares. Para a execução das suutras, utilizouse agulha obtida de cateter endovenoso 20GAX1.16IN e nylon monofilamento de 0,3 mm, aplicando-se uma sutura em U por pálpebra em animais de até 45 dias de idade e duas para os demais. As suturas, repostas ou substituídas quando necessário, foram mantidas até pelo menos 120 dias de idade dos animais, criando uma eversão palpebral permanente que impediu o desenvolvimento do entrópio. Observou-se uma rápida recuperação das lesões bulbares após a aposição das suturas. Os animais foram acompanhados até os 12 meses de idade, época em que atingiam seu desenvolvimento pleno, para se verificar o aparecimento de eventuais alterações palpebrais. As suturas eversoras temporárias mostraram-se de execução simples e rápida, sem complicações pós-operatórias importantes e eficientes na correção do entrópio de desenvolvimento quando aplicadas em animais com menos de 90 dias de idade.

Noggin overexpression inhibits eyelid opening by altering epidermal apoptosis and differentiation.

Contact of developing sensory organs with the external environment is established via the formation of openings in the skin. During eye development, eyelids first grow, fuse and finally reopen, thus providing access for visual information to the retina. Here, we show that eyelid opening is strongly inhibited in transgenic mice overexpressing the bone morphogenetic protein (BMP) antagonist noggin from the keratin 5 (K5) promoter in the epidermis. In wild-type mice, enhanced expression of the kinase-inactive form of BMPR-IB mediated by an adenovirus vector also inhibits eyelid opening. Noggin overexpression leads to reduction of apoptosis and retardation of cell differentiation in the eyelid epithelium, which is associated with downregulation of expression of the apoptotic receptors (Fas, p55 kDa TNFR), Id3 protein and keratinocyte differentiation markers (loricrin, involucrin). BMP-4, but not EGF or TGF-alpha, accelerates opening of the eyelid explants isolated from K5-Noggin transgenic mice when cultured ex vivo. These data suggest that the BMP signaling pathway plays an important role in regulation of genetic programs of eyelid opening and skin remodeling during the final steps of eye morphogenesis.

Age-related changes in anthropometric measurements in the craniofacial regions and in height in Down's syndrome.

This cross-sectional study analyzed age-related changes in normal and abnormal measurements of the head and face in three age categories in 115 Down's syndrome patients 1 to 36 years old. The frequency of normal measurements significantly surpassed that of abnormal ones in each category. Clinically, the key task was to ascertain differences between the youngest and oldest patients. In age group 1 (1 to 5 years), normal measurements in three of the six craniofacial regions were significantly more frequent than abnormal ones. In age group 2 (6 to 15 years) the percentage of normal measurements significantly increased, influenced by higher growth rates in the period of maturation, which coincided with this category. In age group 3 (16 to 36 years) the percentage of normal measurements significantly increased in the head and ear but decreased in the other regions, significantly in the orbits. The frequency of both optimal and severely abnormal measurements changed significantly from age group 1 to 3 in only five measurements each, with no consistency in the direction of results. Abnormal measurements qualified as stigmata and were recorded in 40% (10 of 25) in five regions: three in the face; two in each of the head, orbits, and ears; and one in the nose. Marked epicanthi covering the endocanthion decreased from 35.0% in age group 1 to 8.7% in group 3. In age group 1, the frequency of normal body height (20.7%) in both sexes was significantly less than subnormal (70.3%) but significantly decreased in age group 2. Mean height in group 3 was enough to rule out short stature as a stigmata of Down's syndrome. The study was limited by small numbers, particularly in the variations of normal and abnormal, but the trend toward normality after maturation suggests that reconstructive surgery should be delayed until this time.

A novel mutation in the FOXL2 gene in a patient with blepharophimosis syndrome: differential role of the polyalanine tract in the development of the ovary and the eyelid.

Blepharophimosis/ptosis/epicanthus inversus syndrome (BPES) is an autosomal dominant disorder characterized by abnormalities of the eyelids. We herein report a 12-year-old girl with BPES who had bilateral blepharophimosis, ptosis, hypertelorism, and downslanting palpebral fissures. Mutation analysis revealed the insertion of a cytosine (dup 1036C) within a wild-type run of six cytosines. A comparison of the phenotypic outcomes of the previously described mutations and the dup 1036C mutation reported herein suggest that the outcome is largely dependent on the involvement of the polyalanine tract (residues 221 to 231). We suggest that the polyalanine tract may have a differential role in eyelid and ovarian development and function. Further work is required to clarify whether ovarian function can be predicted on the basis of genotype.

Effects of dexamethasone on tooth eruption in rats: differences in incisor and molar eruption.

A requirement for tooth eruption is the resorption of alveolar bone. Because bone resorption is stimulated by dexamethasone both in vivo and in vitro, dexamethasone 21-phosphate, a soluble form of dexamethasone, was injected into rats to determine its effect on tooth eruption. Such dexamethasone injections accelerate the time of intra-osseous eruption in rat incisors but do not accelerate the eruption time of rat molars when injected into rats. The injections of dexamethasone 21-phosphate also accelerate the time of eyelid opening in the postnatal rats, as well as retarding growth, as measured by body weight. These effects of dexamethasone 21-phosphate parallel the effects of epidermal growth factor injections, including the absence of an effect on molar eruption. This suggests that the molecular signals for the initiation of tooth eruption (i.e., onset of bone resorption) differ between rat incisors and molars. Given that rat incisors are teeth of continuous eruption whereas rat molars are teeth of limited eruption, as are human teeth, care must be taken in extrapolating results derived from rat incisors to human dentition. In vitro, dexamethasone has no effect on the gene expression of either osteoprotegerin or epidermal growth factor in dental follicle cells derived from molars. Because osteoprotegerin expression during normal tooth eruption is transitorily inhibited early postnatally in the molar dental follicle to allow osteoclast formation, the absence of inhibition of its expression by dexamethasone could explain why dexamethasone does not accelerate eruption in molars.

Disinsertion of the levator aponeurosis from the tarsus in growing children.

To confirm when the levator aponeurosis is disinserted and how the disinsertion is compensated for in growing children, the earliest and latest photographs of the same children were the subjects of a retrospective comparative study regarding upward displacement of the superior palpebral crease and the eyeball in the palpebral fissure. Ninety-four children (48 boys and 46 girls) were selected from 615 patients with cleft lip and palate who were followed for more than several years at our outpatient clinic and whose 58,000 photographs were digitized. The earliest and latest photographs of the patients were taken in primary gaze position; the former, taken at less than 3 years of age, and the latter, taken at more than 6 years of age, were selected for this study. The intervals between the two photographs ranged from 3 to 14 years (mean, 9.61 years; SD, 3.11). The superior palpebral crease moved upward parallel with the growth of the children (p < 0.0001) as well as with the length of the growth period (p = 0.0141). The lower eyelid did not move downward (p < 0.0001). The eyeball also displaced upward parallel with growth (p < 0.0001) and with the length of the growth period (p = 0.0302). The more the superior palpebral crease was displaced upward, the more the eyeball was displaced upward (p = 0.0005). The levator aponeurosis may be likely to disinsert from the tarsus in growing children, thus requiring compensatory, excessive contraction of the levator muscle, which may cause upward displacement of the superior palpebral crease. Subsequently, excessive contraction of the superior rectus muscle in conjunction of the levator muscle may rotate the eyeball upward, which may incline the head. When the head is not inclined in the primary gaze position, compensatory contraction of the inferior rectus muscle to maintain the horizontal visual axis may displace the eyeball upward in the orbit by means of the inferior suspensory ligament of Lockwood.

Intraorbital tissue expansion in the management of congenital anophthalmos.

Seven cases of intraorbital tissue expansion for the treatment of congenital anophthalmos or microphthalmos are presented. The ages of the patients at insertion of the expander ranged from 4 months to 8 years. A 4 ml spherical tissue expander with a remote injection port was inserted into the affected orbit via a bicoronal approach. Expansion periods ranged between 4 months and 3 years and are continuing in 2 patients. Results were assessed by clinical examination, comparison of photographs, 3D CT scans and orbital measurements taken from axial CT scans which were compared with established normal values. Results confirmed enlargement of the orbit with expansion. Long-term expansion over several years established near normal bony growth patterns. Placement of the expander within the orbital soft tissue cone resulted in more symmetrical expansion than subperiosteal placement. An osteotomy releasing the lateral orbital wall in older children allows expansion of the orbit and may reduce the incidence of expander extrusion. Although intraorbital tissue expansion successfully induces orbital growth, improvement in the form and size of the congenitally deficient eyelids is less marked.

Effect of the X-linked gene Tabby (Ta) on eyelid opening and incisor eruption in neonatal mice is opposite to that of epidermal growth factor.

Studies on eyelid opening and incisor eruption in 216 neonatal Tabby (Ta)-bearing mice and wildtype controls (35 Ta/Y, 62 + /Y, 30 Ta/Ta, 57 Ta/+ and 32 +/+) showed that in animals hemizygous and homozygous for Ta, the timing of eyelid opening and incisor eruption was significantly delayed (P less than 0.05). It was also observed that once open, the eyes of mutant pups do not remain open for long but soon close again for several days before reopening. An iterative eyes open-eyes closed process seems to continue beyond puberty. Studies in 25 epidermal growth factor (EGF)-treated mutants and 23 saline-treated controls showed that neonatal EGF injections (4 micrograms g-1 body weight per day) reversed the delayed timing of eyelid opening and incisor eruption in hemizygote and homozygote Tabby mice. However, both mutant and wildtype EGF-treated mice also showed the eyes open-eyes closed cycle, whereas untreated nonmutant mice did not. Because Tabby appears to be genetically homologous to the gene for human X-linked hypohidrotic ectodermal dysplasia, these results may have potential clinical significance. The eyes open-eyes closed cycle may involve cycling levels of EGF receptor; since the gene for this receptor shows homology with an oncogene, this system may be useful in studies on genetic control of oncogene function.

Effects of lys-beta-urogastrone in vivo.

Lys-beta-urogastrone, an analogue of human beta-urogastrone with an additional N-terminal lysine, was shown to have similar effects in mice and sheep to mouse epidermal growth factor (mEGF). Lys-beta-urogastrone in doses of 0.18-3.24 micrograms g-1 body weight caused both precocious separation of eyelids and eruption of incisors in neonatal mice. In 17 sheep, intravenous infusion of the urogastrone analogue over c. 24 h led, towards the end of infusion, to erythema of the muzzle, caused reductions in voluntary food intake (with doses greater than or equal to 50 micrograms kg-1) and generally easier manual harvesting of the fleece (with infusions greater than or equal to 81 micrograms kg-1), with spontaneous shedding of the fleece (c. 14 days after infusions of greater than or equal to 116 micrograms kg-1). In five sheep infusions of 25, 38, 50, 83 and 118 micrograms kg-1 fleece-free body weight, plasma concentrations of lys-beta-urogastrone were near maximal 20 h after the infusions started and were, respectively, 1.1, 1.7, 5.5, 18 and 79 micrograms l-1 plasma. Plasma concentrations of gastrin, somatostatin and pancreatic polypeptide were determined in these five sheep. Plasma gastrin rose sixfold by the end of infusions of 25 micrograms kg-1 of the urogastrone analogue, and tenfold with the higher doses of infusion. Although plasma somatostatin concentrations were variable, a consistent trend was observed; lower levels were apparent during the lys-beta-urogastrone infusions. There was no discernible trend in pancreatic polypeptide concentrations.

Physiological effects of transforming growth factor in the newborn mouse.

Transforming growth factor-type alpha accelerated incisor eruption and eyelid opening in the newborn mouse and also retarded the growth rates of hair and body weight when administered in high dosage (0.7 to 4 micrograms per gram of body weight). The results of whole animal studies indicate that transforming growth factor-type alpha and epidermal growth factor do not differ significantly in these effects and suggest that transforming growth factor-type alpha may be important in immature animals.